- Voiced by: Masao Nasakone (stock grunts), Isao Yatsu (series), Jiro Dan (Ultraman Mebius onwards)
- Expy: Of the original Ultraman, whom he was originally intended to be. Of all the Ultra heroes, Jack has the closest resemblance to him; not to mention, he has many of Ultraman's abilities, including the Specium Ray and Ultra Slash.
- Meaningful Name: Jack is a popular name for heroes in English fairy tales, hence why the producers selected it as the characters name.
- No Name Given: In the Showa era shows (including his debut series), he had no name and was only known by a variety of titles like Returning Ultraman, New Ultraman, and even Ultraman II. "Ultraman Jack" was only decided upon in 1984, using the scrapped named for Ultraman Taro.
- Swiss Army Weapon: The Ultra Bracelet, which can transform into anything Jack desires from a bomb to a lance to a boomerang to a shield.
- What Do They Fear Epiosde: Jack is deathly afraid of Zetton. Half of the conflict in the last episode comes from Jack refusing to fight the resurrected Zetton II alongside Alien Bat. He gets over it in the end, however.
MAT (Monster Attack Team)
- Played by: Jiro Dan
- The Hero: As the main character.
Captain Katsuhiro Kato
- Played by: Nobuo Tsukamoto
- Played by: Shunsuke Ikeda
- Played by: Hatashi Mitsushi
- Played by: Ken Nishida
- Played by: Mika Katsuragi
Captain Ryu Ibuki
- Played by: Negami Atsushi
- Played by: Shin Kishida
- Played by: Rumi Sakakibara
- Played by: Kawaguchi Hideki
- Played by: Iwasaki Kazuko
- First Appearance: All Monsters Attack
- Cephalothorax: The main difference from most examples is that the face is incredibly small in comparison to the rest of the body.
- Everything's Squishier with Cephalopods: Although not obvious at first glance, Takkong is indeed inspired by an octopus (with some sea sponge thrown in), as evidenced by the suckers covering its mass and the "face on a round body" shape.
- Our Monsters Are Weird: A giant sponge-octopus hybrid that eats oil.
- Making a Splash: Can spray jets of water from its mouth and the suckers on the body.
- Sea Monster: Just suddenly appeared in Tokyo Bay one day to battle Zazahn.
- First Appearance: All Monsters Attack
- Expy: Of Hedorah (who debuted around the same time). The two look very similar to each other, and both have similar motives, being drawn to humanity because of the pollution in Tokyo Bay.
- Muck Monster: Sort of. Though it is clearly made of seaweed, Zazahn's title is "Sludge Monster", which was particularly relevant to 70's Japan due to the serious pollution crisis of the time.
- Sea Monster: Like Takkong, it just suddenly appeared out of the deep one day in Japan.
- First Appearance: All Monsters Attack
- Breakout Villain: While not as iconic as the likes of Bemstar and Gudon, Earthtron has proven popular enough to reappeare in many series since it returned in Ultraman Mebius.
- Breath Weapon: A beam of magma.
- Everything's Better with Dinosaurs: Magma-spewing NotZillas!
- Magma Man: His Breath Weapon
- Not Zilla: Earthtron's design was based on Godzilla's (though not designed from a Godzilla suit like Gomess and Jirass). He even had the same designer!
- Spell My Name with an "S": Earthron and Arstron are also used.
- Starter Villain: Although not the first monster to appear in the episode, Earthtron's the first to fight Ultraman Jack.
- Tunnel King: As his name suggests, he's a capable burrower.
- First Appearance: The Evil Monster Realm of Terror
Sadorah has made many more appearances in the Ultra Series. Often, the monster is given some powers though. The fog was made into a creation of Sadorah and it was given extending claws to strike at prey from the fog. Sadorah is often shown as a pack hunter in later appearances too.
- Breakout Villain: Like Earthtron, Sadorah has made a number of reappearances in the franchise, starting with Ultraman Mebius.
- Dirty Coward: Being incredibly weak, Sadorah prefers to use the cover of its fog to strike at enemies.
- Everything's Better with Dinosaurs: Pincer-clawed, fog-making dinosaurs!
- Off with His Head!: Sadorah's death.
- Ominous Fog: In its original appearance, the fog was everywhere, but natural. Later appearances had Sadorah create the fog for stealth attacks. It also has EMP properties interestingly.
- Power Pincers: Sadorah's claws, which have become Extendable Arms in later appearances.
- Spell My Name with an "S": Has also been spelled Sadora, Sadola, and Sadolar.
- Villain Team-Up: With Detton when Jack showed up to kill both of them.
- First Appearance: The Evil Monster Realm of Terror
- Everything's Better with Dinosaurs: Since Detton is meant to be a Telesdon lookalike.
- Expy: Of Telesdon, unless the statements from Ultraman monster books claiming Detton is Telesdon's relative are true. In fact, Detton's role was originally meant for Telesdon, with the only physical differences being that Detton is a muddier colour and a stouter snout.
- Long-Lost Relative: According to some sources, Detton is Telesdon's sibling. Helps that Detton was created with the original (albeit significantly aged) Telesdon suit.
- Villain Team-Up: With Sadorah once Jack showed up to fight them, even though they had been clashing with each other just minutes ago.
- First Appearance: Certain Kill! Comet Kick!
- Achilles' Heel: Its horns are the source of its powers, so snapping them off renders Kingsaurus III helpless.
- Barrier Warrior: Can conjure a force field strong enough to block a Specium Ray. However, the top is left open to attack.
- Breath Weapon: Atomic breath, or rather a "U-235 Beam".
- Eat Dirt, Cheap: Feeds on uranium.
- Everything's Better with Dinosaurs: Atomic, superpowered, sail-backed dinosaurs!
- Horn Attack: Asides from the obvious goring (which it uses to briefly cripple Ultraman Jack), Kingsaurus III can fire a variety of energy attacks from its horns.
- I Love Nuclear Power: Gained its powers from the consumption of radioactive minerals. Helps that it can also breath radiation like Godzilla.
- Mix-and-Match Critters: Sort of a mix of a Spinosaurus and a Triceratops.
- Mythology Gag: The "III" is because Kingsaurus III is the third "king" monster with the first being Red King and the second being Elekingnote . It's a bit of a subtle one so not too many fans have picked up on it.
- Prehistoric Monster: According to an unused script though, it's actually from the sunken continent of Atlantis!
- Shock and Awe: Touching Kingsaurus III's horns delivers an electric shock to prevent opponents from simply grabbing and tearing them off.
- Tunnel King: Capable of burrowing just as well.
- Wake-Up Call Boss: The first monster to deliver a serious challenge to Jack and defeat him, forcing Goh to train hard for the first time.
- First Appearance: Two Giant Monsters Attack Tokyo
Twin Tail has made many more appearances in the Ultra Series. As you might guess, it's almost always with its arch-nemesis Gudon. The monster's bizarre design would go on to inspire many other creatures like Litomalus and Mukadendar, as well as the popular twin tail hairstyle in Japan.
- Achilles' Heel: The two glowing spots near its tails are sensory organs. Harming those causes Twin Tail great pain.
- Arch-Enemy: Gudon, of course.
- Badass Normal: Having no powers didn't stop Twin Tail from overwhelming Ultraman Jack in their first fight (albeit with some help from Gudon, who wasn't any very pleased with the hero intruding on their fight either).
- Breakout Villain: Not to the extent of Gudon below, but Twin Tail is quite popular for his unorthodox design.
- Eye Scream: MAT blows out both of its eyes.
- Food Chain of Evil: The natural prey of Gudon.
- Multiple-Tailed Beast: The name is Exactly What It Says on the Tin. Two tails.
- Our Monsters Are Weird: The sheer weirdness of his design would inspire dozens of other kaiju with heads on their bottoms and tails on their tops.In fact, it's why Twin Tail's one of the most iconic kaiju of the Ultra Series.
- Poisonous Person: Kishida states that Twin Tail has a venomous bite, but nothing else in the series has ever indicated that, nor is it ever brought up again.
- Prehistoric Monster: Simple as that.
- Tail Slap / Prehensile Tail: Obviously Twin Tail's main weapons. They're also capable of throttling Ultras if necessary.
- Tunnel King: Twin Tail is highly proficient burrower.
- Whip It Good: The two tails. They also have nasty little spikes for extra effect.
- First Appearance: Two Giant Monsters Attack Tokyo
Gudon has become one of Ultraman Jack's most iconic foes and has reappeared numerous times in the Ultra Series (though not always with Twin Tail). Like Twin Tail, Gudon's design would also inspire other monsters with whip-like arms.
- Arch-Enemy: Of Twin Tail, who also happens to be its natural prey.
- Badass Normal: Despite having no powers, Gudon has proven to be one of the most formidable foes that Ultramen have faced.
- Breakout Villain: Along with Bemstar and Alien Nackle, Gudon has appeared in almost every Ultraman series since Ultraman Mebius.
- Everything's Better with Dinosaurs: Whip-armed dinosaurs!
- Food Chain of Evil: The predator of Twin Tail and more dangerous than it.
- Prehistoric Monster: Just like Twin Tail. It's even stated to have hailed from the Jurassic period.
- Tunnel King: Although many have questioned how it burrows with whip-like arms. According to Ultraman Mebius, those whips are tentacles that vibrate earth to weaken it.
- Whip It Good / Combat Tentacles: Its weapon of choice. They're powerful enough that a single whiplash can smash through solid stone.
- First Appearance: Operation Rainbow Monster
- Breath Weapon: A stream of fireballs.
- Chameleon Camouflage: Its main ability, as the camouflage is so strong that it effectively renders the monster invisible. Thus, MAT decides to spray the monster with an assortment of bright paints as a countermeasure. Additionally, its skin is textured to resemble the rocky mountains it inhabits.
- Everything's Better with Dinosaurs: More of a chameleon-based kaiju, but it certainly resembles the part.
- Non-Malicious Monster: Gorabagos was just sorta minding its own business, but MAT attacked it anyways when Jiro's camera spotted it.
- See the Invisible: Asides from the titular paint-spraying operation performed on the monster, cameras will always capture Gorbagos no matter how well-camouflaged.
- First Appearance: Monster Time Bomb
- Achilles' Heel: Ghostron has extremely poor eyesight. Fortunately, his hearing compensates.
- Breath Weapon: A heat beam, not unlike Earthtron's magma beam.
- Everything's Better with Dinosaurs: Well, it was made from a modified Earthtron suit.
- Long-Lost Relative: Some books on Ultra monsters claim it's the sibling of Earthtron due to the fact that the two monsters are made from the same suit.
- Non-Malicious Monster: Like Gorbagos, Ghostron was just minding his own business, but MAT decided he had to die. Unlike Gorbagos, this only makes things worse when a powerful bomb gets stuck on its tail, making the situation much more dangerous for Japan.
- Why Am I Ticking?: The entire episode was basically about MAT trying to remove an extremely powerful bomb stuck on Ghostron's body. The monster doesn't seem to be aware of the bomb though.
- First Appearance: Monster Island S.O.S.
- Beware the Silly Ones: Despite Dangar's goofy appearance and behaviors (it has dreadlocks and moves by dancing!), it's still by no means a friendly monster.
- Hook Hand: In the form of simple one-clawed hands.
- Non-Malicious Monster: Dangar was content to live on the island so long as it was left alone. However, it wasn't very friendly towards anybody else stepping into its territory, so MAT had to kill it.
- Spell My Name with an "S": Has also been spelled Dunger, Danger, and Dungar.
- First Appearance: Dinosaur Explosion Directive
- Breath Weapon: Can spray a fire extinguishing mist from its mouth. While it uses this ability for the sole purpose of foiling a plan by MAT, it also serves handy for blinding Ultraman Jack in the episode's fight.
- Dem Bones: The animated skeleton of an already dead prehistoric kaiju.
- Everything's Better with Dinosaurs: Undead dinosaurs!
- Hollywood Acid: Capable of dissolving humans in seconds, but curiously, has no effect on buildings.
- The Juggernaut: Totally immune to the Specium Ray.
- Karma Houdini: Stegon's punishment for killing people, smashing buildings, and causing general destruction? Nothing! And, why? Because a bunch of kids begged Ultraman Jack to spare it!
- Ninja Zombie Pirate Robot: It's an acid-spitting zombie brontosaurus, what more could you want?
- Red Eyes, Take Warning: The only hint of life in its body.
- Stars Are Souls: Turned into a constellation by Jack, though not without the difficulties of subduing the monster first.
- Super Spit: Its acidic drool.
- First Appearance: Poison Gas Monster Appears!
- Breath Weapon: Breathes a toxic gas that has similar properties to mustard gas. However, it doesn't have much o an effect on Ultraman Jack.
- Deadly Gas: Mogunezun is intended to be for mustard gas and other chemical weapons as Godzilla is to nuclear radiation and the atomic bomb.
- Does This Remind You of Anything?: The kaiju was pretty much created by the screenwriters as a commentary on Japanese usage of chemical weapons in the Second World War, with the usage of mustard gas been treated very seriously here.
- Everything's Better with Dinosaurs: Prickly, poisonous dinosaurs!
- Poisonous Person: Breathes toxic gas and feeds on poisonous substances to strengthen its own toxins.
- Spikes of Doom: Well, more like floppy quills of doom, but they're still loaded with enough deadly poison to give Ultraman Jack some trouble.
- Tunnel King: Gets around unnoticed by burrowing.
- First Appearance: Revenge of the Monster Shugaron
- Breath Weapon: A heat beam.
- Expy: While there is no physical resemblance, it borrows traits from Hydra and Woo, as like the former its attacks target roads and drivers, while like the latter it's implied to be the protective spirit of a deceased parent.
- Eye Scream: Thanks to MAT's firepower, though it only makes Shugaron even more furious.
- Non-Malicious Monster: Shugaron was completely content to be left alone, only rampaging when traffic started coming into the Shirakami Mountains.
- Our Ghosts Are Different: It's implied that Shugaron is in fact the vengeful spirit of an artist who liked to come to the region to paint its beautiful scenery, coming back as a monster to punish humanity for disturbing the landscape.
- Tragic Monster: In some ways, Shugaron's rampage is justified, as the episode goes to great lengths to emphasize the Scenery Porn of its home that is being taken down for a busy highway. Made even more tragic by how it kills the artist's daughter in its rampage.
- First Appearance: Terror of the Tsunami Monsters - Tokyo's Big Pinch
- Battle Couple: With Seagorath. She proves to be easily overwhelmed by MAT firepower alone, but when she calls in her mate, the tables are turned.
- Bizarre Sexual Dimorphism: They're a mated pair, but Seamons is a stout rhino-like quaduped, while Seagorath is a towering dragon-like biped.
- Blow You Away: Can create tornadoes like Seamons.
- Combination Attack: Seamons and Seagorath utterly devastate Tokyo with their combined powers, including the creation of an gargantuan tsunami in Tokyo Bay.
- Horn Attack: Shoots lightning from her horn.
- Making a Splash: Can create tsunamis, as suggested by her subtitle "Tsunami Monster".
- Punny Name: She's a sea monster named Seamons.
- Sea Monster: A rhinoceros-like monster that spent its time attacking ships.
- Shock and Awe: Can shoot lightning from her nose horn and create thunder.
- Weather Manipulation: By using her horn, she can conjure typhoons, hurricanes, and lightning storms.
- What Happened to the Mouse?: Seagorath dies of his injuries shortly after Ultraman Jack blows off his horn, hence being revived by Alien Nackle, but Seamons' fate is left unanswered, with her last appearance being fleeing with her mate back to the sea.
- First Appearance: Terror of the Tsunami Monsters - Tokyo's Big Pinch
- Achilles' Heel: Destroying Seagorath's horn renders him totally powerless. No word on if the same applies with Seamons.
- Back from the Dead: Thanks to Alien Nackle.
- Battle Couple: With Seamons.
- Bizarre Sexual Dimorphism: They're a mated pair, but Seamons is a stout rhino-like quaduped, while Seagorath is a towering dragon-like biped.
- Blow You Away: Can conjure huge windstorms, as suggested by his subtitle "Tornado Monster".
- Combination Attack: His powers are already formidable alone, but with Seamons' they become almost godlike.
- Horn Attack: Shoots lightning from his horn.
- Making a Splash: Can create tsunamis like Seamons.
- Sea Monster: A dragon-like monster that spent its time attacking ships.
- Shock and Awe: Can shoot lightning from his nose horn and conjure lightning.
- Spell My Name with an "S": Also referred as Seagoras.
- Weather Manipulation: By using his horn, he can conjure typhoons, hurricanes, and lightning storms.
- First Appearance: Revenge of the Monster Lad
- Breath Weapon: A bright blue beam of electrical energy.
- Energy Absorption: It needs to consume elctricity in order to maintain its electrical powers. The invisibility is a separate asset.
- Expy: Of Neronga from the original Ultraman, another electricity-eating quadruped able to turn invisible.
- Invisibility: Eledortoise's main ability. Unlike Neronga, it can turn invisible at will instead of needing to consume electricity to power it.
- Shock and Awe: Eledortoise is capable of electrifying its body and shooting a powerful cluster of lightning from the two prongs on the rear end of its shell.
- Spell My Name with an "S": Eledortoise or Eledortus?
- Turtle Power: Specifically, its a softshell turtle.
- First Appearance: Mystery of the Giant Bird Monster Terochilus
- Blow You Away: Like most winged kaiju, it can create enormous gusts with its wings.
- Breath Weapon: A spray of webbing that it normally uses to create its roost, though they're perfectly useful in entangling Ultramen as well. And in a slight variant, Terochilus can fire energy bullets from its nose.
- Feathered Fiend: Even if it is lacking in feathers (they're all on the head and neck), Terochilus is a surprisingly formidable monster.
- Giant Flyer: It's a 60-meter-tall pterodactyl-bird monster, what did you think?
- The Juggernaut: Asides from taking two episodes to defeat, it also survived two direct hits from the Specium Ray.
- Prehistoric Monster: An Archaeopteryx-based kaiju that resembles a pterodactyl.
- Ptero Soarer: A kid even misidentifies it as Rodan! However, Terochilus is actually based on Archaeopteryx, but you have to remember that kaiju are never supposed to be realistic.
- First Appearance: Ultraseven Arrives!
Due to being one of Ultraman Jack's most dangerous and famous opponents, as well as appearing in the first episode to have Ultras from different shows meet, Bemstar has become a staple of the Ultra Series. Almost always a formidable opponent for the Ultramen, Bemstar's energy-consuming abilities make it a constant pain for our energy-using heroes.
- Back from the Dead: Twice actually. First was by Alien Nackle to study Jack's combat and second was by Yapool in Ultraman Taro.
- Belly Mouth: That weird pattern on its belly? That's its second mouth (referred by many as the gorge), or the one it uses to eat energy attacks.
- Big Eater: Especially for energy.
- Breakout Villain: Has appeared in nearly every series since Ultraman Mebius. Up there with the likes of Gomora, Red King, Zetton, and Eleking for most popular and iconic Ultra monsters.
- Breath Weapon: Some artwork for the Ultra Series depicts Bemstar as being able to breathe a beam of energy, but that has never appeared in the shows.
- Energy Absorption: Thanks to its Belly Mouth. However, the way the mouth does so varies from series to series.
- Extreme Omnivore: Although energy is the mainstay of Bemstar's diet, living beings and machinery have also been consumed by the monster's gorge.
- Giant Flyer: As a bird-like kaiju, although it mainly flies through space instead.
- Horn Attack: Shoots energy bolts from the small horn on its head.
- No-Sell: Beam attacks have absolutely no use against Bemstar as it simply eats them up. Slicing attacks, on the other, hand...
- Off with His Head!: His fate, though Jack also chops off its wings for a good measure.
- Villainous Glutton: Bemstar has a ravenous appetite for energy of any sort. In fact, the reason why it comes to Earth is because Earth's energies are specially delicious to the monster.
- The Worf Effect: In its original appearance as Ultraman Jack's most deadly foe up to that point. Has kept this reputation in later appearances.
- First Appearance: The Giant Invisible Monster from Outer Space
- Came from the Sky: The first indication of its existence is a meteorite-egg-thing that hatches out nothing...until buildimgs start getting smashed by an unseen force!
- Gonk: Considered by many fans to be one of the most grotesque-looking monsters in the Ultra Series, which can be attributed to its long and sparse hairs, incredibly wrinkly skin, and the fact that elephant-based kaiju aren't very common.
- Invisibility: The episode gives us Exactly What It Says on the Tin. Sartan generally prefers to remain invisible, only revealing when attacked or fighting.
- Our Monsters Are Weird: An extraterrestrial elephant that can turn invisible!
- The Shadow Knows: Sartan's enormous shadow will always remain visible.
- First Appearance: The Monster is a Shooting Star in Space
- Breath Weapon: A stream of flames.
- From a Single Cell: Magnedon can regenerate from being blown to pieces within the course of a few hours.
- Gentle Giant: A purely peaceful creature, but MAT and Ultraman Jack had to try kill it anyways due to the inconveniences of living alongside a magnetic kaiju. Jack even feels quite bad after killing Magnedon.
- Magnetism Manipulation: Its body constantly emits magnetic waves, capable of pulling a jumbo jet straight out of the sky.
- Selective Magnetism: Magnedon is also able to magnetize targeted objects, as it does with Ultraman Jack in the episode's fight.
- Sleepyhead: Magnedon spends a large chunk of the episode asleep and completely oblivious to both the destruction it inadvertently causes and MAT's attempts to kill it.
- Stars Are Souls: Ultraman Jack creates a constellation of Magnedon after killing it, somewhat similar to what he did with Stegon.
- First Appearance: Monster Channel
- Blinded by the Light: Can create a disruptive aurora of light in order to blind airplane pilots and cause midair collisions.
- Cute Little Fangs: Two of them just underneath its nose. Surprisingly, they're capable of hurting Ultraman Jack.
- Do Not Adjust Your Set: Beacon's main gimmick is that its presence messes with radio, radar, and television signals, creating interference and causing the TV to see whatever it sees.
- Eye Beams: Strong enough to shoot down planes and contest with the Specium Ray.
- Our Monsters Are Weird: Easily one of the weirdest critters created for the Ultra Series, being a bug-eyed, spike-backed monster able to manipulate television waves and fly by floating on its belly.
- First Appearance: I Will Kill This Monster
- Breath Weapon: A spray of mist that turns into sticky webbing upon contact with solid material in order to slow down opponents and disrupt MAT's fighter jets.
- Bullet Catch: Can do the kaiju equivalent of this with missiles, thanks to its surprisingly swift reflexes. It can even catch this with its teeth without harm (although Ultraman Jack finds a way to take advantage of that)!
- Everything's Better with Dinosaurs: Garbage dump-living dinosaurs! However, its motifs are drawn from rats and cockroaches, befitting its love of garbage.
- Meaningful Name: Gokinezula's name is a combination of "gokiburi" ("cockroach") and "nezumi" ("rat"), which refers to its love of garbage and association with areas filled with trash and filth.
- Your Head Asplode: Its fate caused by catching a missile with its mouth that Ultraman Jack then detonates with a Specium Ray.
- First Appearance: Dark Monster, Spit Out the Stars!
- An Arm and a Leg: Jack tears off Zanika's claws during the fight, forcing the monster to beg for mercy. Mercy is granted, and after Zanika's homeworld is restored by Jack defeating Vacuummon, thepincers grow back.
- Giant Enemy Crab: From the constellation of Cancer fittingly enough.
- Invading Refugees: Zanika came to Earth to escape Vacuummon's hunger, and is normally a pretty peaceful guy, but due to having gone berserk from the loss of its homeworld and MAT just being worried about the presence of a giant alien monster, it had to be dealt with. Fortunately, Ultraman Jack spares Zanika and the monster even warns him of Vacuummon's arrival.
- Super Spit: Constantly drools paralyzing foam from its mouth that it can spit at enemies.
- First Appearance: Dark Monster, Spit Out the Stars!
- Blob Monster: Probably one of the biggest ever imagined.
- Eat Me: Used by Jack, who then slashes Vacuummon up from the inside with the Ultra Bracelet like a knife to a plastic bag.
- Eldritch Abomination: A titanic nebulous blob-like entity that consumes planets.
- Planet Eater: Though it also consumes stars, as the characters notice some of the constellations disappearing as it makes its way to Earth.
Kupukupu / Kingstron
- First Appearance: Horror! Birth of the Mansion Monster!
- Adaptive Ability: Killing Kupukupu allows the monster to mutate by merging any inanimate matter that its remains come in contact with, eventually regenerating into a completely new monster.
- Art Initiates Life: The surviving piece of Kupukupu slowly evolves into Kingstron by appearing as a drawing on a kid's bedroom wall that develops Kingstron's features and also gets bigger and more lifelike.
- Breath Weapon: Kingstron breathes fire.
- From a Single Cell: As Kupukupu. Overlaps with Adaptive Ability.
- The Juggernaut: Kingstron was not fazed by the Specium Ray.
- Humans Are the Real Monsters: Kupukupu was a totally defenseless and innocent monster blown up solely for being from space. MAT paid dearly when it resulted in the 60-meter-long Kingstron trashing Tokyo.
- Metamorphosis Monster: Kupukupu is a small, white, featureless quadruped, but after merging with the walls of a house, it transforms into Kingstron, a horned tortoise-like kaiju with spikes on its shoulderblades.
- Spikes of Doom: Kingstron has these on its back. They're capable of rotating too, allowing the monster to turn itself up if flipped over. They also fire energy bolts.
- Stripped to the Bone: Kingstron's fate.
- Turtle Power: Kingstron, who looks sorta like Black King as a turtle.
- Woobie, Destroyer of Worlds: A perfectly harmless monster turned into a not-so-harmless one by human mistrust and prejudice.
- First Appearance: Leaving My Home Planet Earth
- Breath Weapon: A stream of fire.
- Everything's Better with Dinosaurs: It certainly resembles the part, though with a big leaf-shaped tail suggesting geckos to be the main motif.
- Magnetism Manipulation: Zagoras' meteor-vessel magnetizes loose objects in its vicinity to add to its mass, so the monster smashes structures and tears up the earth in order to get large chunks of material for the meteor-thingy.
- Non-Malicious Monster: Zagoras only wanted to leave Earth and that was it. Unfortunately, its method of doing so was too dangerous for humanity, so MAT and Ultraman Jack have to kill it.
- Spell My Name with an "S": Zagoras or Zagorath?
- First Appearance: Mystery! Homicidal Beetle Incident!
- Big Creepy-Crawlies: It's normally about the size of a relatively large stag beetle, but it turns into a kaiju at the end of the episode.
- Death Ray: Can shoot them from its single antenna.
- Eye Scream: Thanks to MAT, allowing Jack to cut off it antenna.
- The Juggernaut: Another of those monsters that casually brushes off the Specium Ray in order to have Ultraman Jack use another power instead.
- Make My Monster Grow: MAT's firepower somehow causes Nokogirin's size to increase from that of a standard bug to that of a Kaiju in the span of a few hours.
- First Appearance: Go to Hell with This One Blow!
- An Arm and a Leg: Ultraman Jack rips off both of Gronken's arms, but the monster continues to fight!
- Chainsaw Good: Gronken's body is covered in buzzsaws, but the ones that it utilizes are on its arms, which are capable of slicing through a statue of its size in half.
- Everything's Better with Dinosaurs: Chainsaw dinosaurs!
- Off with His Head!: Ultraman Jack defeats him by kicking off his head.
- Tunnel King: It first makes itself known by bursting from beneath the ground, and retreats by burrowing back underground.
- First Appearance: Ultra Special Attack
- Blow You Away: Can spin its dome rapidly to levitate and create a tornado in the process.
- Breath Weapon: Toxic gas.
- Cephalothorax: The suit actor's head is hidden in the dome.
- Combat Tentacles: Its arms and tail.
- Having a Blast: Varricane can flash the red spots on its dome to create explosions.
- The Juggernaut: Was totally unfazed by the Specium Ray, so Jack simply defeated it by bringing it into space where it froze to death in the lack of atmosphere.
- Making a Splash: Varricane's presence is near-constantly surrounded by torrential downpour.
- Our Monsters Are Weird: Being a giant jellyfish that can control the weather is one thing, but every other little things about it makes it all the more bizarre.
- Sea Monster: A giant jellyfish from Micronesia.
- Shock and Awe / Electric Jellyfish: Can deliver powerful electric shocks by grabbing enemies and create lightning storms.
- Weather Manipulation: Can conjure rainstorms and hurricanes much like Seamons and Seagorath before it.
- First Appearance: Jiro Rides a Monster
- Bilingual Bonus: Comes from "yadokari", or "hermit crab" in Japanese.
- Giant Enemy Crab: A hermit cab to be precise.
- Hollywood Acid: Can spray acid from its pincers.
- Impaled with Extreme Prejudice: Its fate when Jack turns the Ultra Bracelet into a lance. And then it catches on fire for a good measure.
- Non-Malicious Monster: Yadokarin's sole crime was making its shell out of a broken space station that Jiro happened to be wandering about inside, but MAT attacks it anyways.
- First Appearance: Curse of the Skeleton God
- A Load of Bull: Oxter's primary motif is bison, although it really doesn't look anything like one.
- Armless Biped: It drags itself around on only two legs and a tail for support. The suit actor's arms are in its horns.
- Breath Weapon: Acid sprays capable of dissolving a man in seconds.
- Cephalothorax: It really doesn't have an distinction between a head and a body.
- Horn Attack: They act as pincers too.
- Overly Long Tongue: Which can be used as a whip capable of slamming a building down.
- Non-Malicious Monster: Oxter was content to dwell in its cave as long as the graveyard of the bison is undisturbed. Ultraman Jack continues Oxter's duty by sealing off the cave and placing the kaiju's skeleton within.
- Prehistoric Monster: Oxter's the guardian of a cave full of bison fossils, so it's probably of Ice Age origin.
- Spell My Name with an "S": Oxter or Oxster?
- Stripped to the Bone: Its fate.
- First Appearance: In Between a Devil and an AngelPlayed by: Tetsuya Kaji (voice), Teruo Kazama (human form actor)
- Bitch in Sheep's Clothing: Since only Hideki Goh is able to hear Zelan's taunts and warnings, the other MAT members just see Goh bullying a little kid, which gets him briefly expelled from MAT. Only Captain Ibuki is willing to listen to Goh's accusations of the kid being an evil alien, but even he is reluctant as he doesn't to get judgmental.
- Creepy Child: In the form of the little boy. Some of the shots they use to show of him communicating with Goh certainly make him even creepier.
- Death Ray: Able to fires a blue one from the ridges on its face where most beings would have eyes.
- Eyeless Face: He only has a series of bumpy ridges that act as his eyes.
- Manipulative Bastard: Spends the episode tormenting Goh and even enticing him to attack the alien in the disguise of a child.
- This Was His True Form: Only appears in his true form at the end of the episode, with later series giving viewers longer glimpses of Alien Zelan's normal appearance.
- First Appearance: In Between a Devil and an Angel
- Breath Weapon: A red beam of energy referred to as the "Pulsar Shot".
- The Juggernaut: Able to survive the Specium Ray without taking much damage.
- Off with His Head!: Its fate.
- Pet Monstrosity: Of Alien Zelan, who used the monster to destroy the city and distract MAT while he isolated Goh from the team to assassinate him.
- Red Herring: Plooma's purpose was to distract MAT from the real villain of the episode — the disguised Alien Zelan. Its Boss Subtitles is even "Decoy Monster".
- Spell My Name with an "S": Plooma or Pluma?
- First Appearance: Decisive Battle Under the Setting Sun!
- Breath Weapon: A spray of paralyzing webbing.
- Fartillery: King Maimai's farts are highly explosive.
- Feed It a Bomb: Jack kills King Maimai by turning the Ultra Bracelet into an explosive and throwing it down the monster's throat.
- Gasshole: King Maimai's farts are so powerful they cause earthquakes!
- Giant Flyer: The sail-like wings on its back help out.
- Metamorphosis Monster: The monster starts off more reptilian in appearance, but then sheds his skin and emerges as the more insect-like form shown here just in time to fight Ultraman Jack.
- Mix-and-Match Critters: Sorta looks like a big cicada mixed with a dinosaur.
- Prehensile Tail: Uses its tail to throttle Jack during the battle.
- Prehistoric Monster: King Maimai was slumbering underground for millions of years before being awoken by miners. However, he's more goofy than menacing, given that his appearance is supposed to be a Breather Episode.
- First Appearance: The Boy and the Monster MasterVoiced by: Kenjiro Uemura (also human form actor)
Having appeared in one of the most critically lauded episodes in the entirety of the Ultra Series, Alien Mates' story would be continued in Ultraman Mebius when the alien's biological son Beo would come to Earth in the award-winning Sequel Episode "The Monster Master's Legacy".
- Alien Blood: Light green.
- Creepy Good: Despite his rather eerie appearance (black pupilless eyes and pale white skin), Mates was essentially a benevolent alien.
- Does This Remind You of Anything?: The murder of Alien Mates by the angry mob was inspired by anti-Korean violence following the Great Kanto Earthquake of 1923, due to rumours that the Korean minority in Japan was engaging in criminal activities to take advantage of the Japanese people's devastated homes.
- Fantastic Racism: A victim of this, and one of the major themes of the episode. In a sad irony, Mates was actually try to build friendly race relations with humans.
- Interspecies Adoption: Mates adopted Yoh, a human, as his son while disguised. This would become an important plot point in Ultraman Mebius when Beo learns about from a schoolteacher who met Yoh as a little girl that the boy had inherited is late adopted father's belief in the possibility of friendly relations between Earth and his people.
- Meaningful Name: "Mates" as in "friend", indicating his goodwill to Earthlings.
- Spell My Name with an "S": Sometimes spelled "Meits".
- Too Good for This Sinful Earth: And how! The first truly good alien in the franchise is killed by a mob of humans. It's revealed in Ultraman Mebius that his adopted human son Yoh also died young, though many years after Mates and long enough for him to pass Mates' beliefs in tolerance.
- First Appearance: The Boy and the Monster Master
Due to his debut episode being among the most well-regarded in the franchise, Muruchi has made many more appearances in the Ultra Series. However, most of Muruchi's appearances since Ultraman Mebius have renamed the monster Zoa Muruchi. This version of Muruchi is, for all intents and purposes, the exact same.
- Breakout Villain: Due to the iconic nature of "The Boy and the Monster Master" among fans, Muruchi is one of Ultraman Jack's most iconic foes, hence his frequent reappearances.
- Breath Weapon: An energy beam that depending on the series is either red or blue.
- Pet Monstrosity: To Alien Mates, though unlike most examples in the franchise, he never used it to conquer Earth. It was purely meant to be a bodyguard for if things went bad.
- Roaring Rampage of Revenge: In its original appearance as well as Ultraman Mebius, where it went on a rampage to punish humans for their racism and prejudice harming Alien Mates.
- Sea Monster: Though he's only been seen underwater in Ultra Galaxy Mega Monster Battle, Muruchi's design is definitely supposed to be one. His Boss Subtitles is even "Giant Fish Monster"
- Woobie, Destroyer of Worlds: Muruchi was not destroying its surroundings in its original appearance because of it was commanded to like most kaiju controlled by aliens, but instead to punish humanity for their hatred leading to Alien Mates' death. Goh even considers not transforming into Jack and letting the villagers reap their sins.
- First Appearance: The Life That Can't Be Forgiven
Leogon is more notable, however, for being a prototype to the Godzilla kaiju Biollante. In fact, Leogon was created by the same scriptwriter of Godzilla vs. Biollante, a then-16-year-old Shinichiro Kobayashi, who had submitted the story as part of a contest held by Tsuburaya Productions long before he used a similiar story for Toho Studios.
- Make My Monster Grow: Grows from a mere two feet to over a hundred and fifty in a matter of hours due to an error in Mizuno's creation of the monster.
- Off with His Head!: Its fate, though Jack also slices off its front legs in the process.
- Planimal: One created via science gone too far, much like its Spiritual Successor, Biollante. To push the point further, Biollante's designer confirmed drawing cues from Leogon in designing her, with some concept art more closely resembling the Ultra kaiju.
- Whip It Good: The tubes on Leogon's back carry vines to use as whips or to wrap around enemies.
- First Appearance: Cruel Light Monster Priz-Ma!
- An Ice Person: It's made out of ice!
- Eldritch Abomination: A living mass of Antarctic ice able to distort reality and absorb all matter is touches.
- Expy: Of Bullton from the original Ultraman. Both are abstract monsters capable of messing up their surroundings via bizarre abilities that even leave an Ultra's head spinning.
- Light 'em Up: Being a prism-based monster, Priz-Ma can use light to create illusions, blind opponents, and cause all sorts of trippiness.
- Meaningful Name: Priz-Ma means "Prism-Demon" in Japanese.
- Our Monsters Are Weird: A giant iceberg that warps reality...This is one of the Ultra monsters that can only be called a kaiju in the vaguest sense of the term.
- Reality Warper: Being based on Bullton, Priz-Ma is fully capable of this, although to an even more surreal degree.
- Spell My Name with an "S": Priz-Ma or Pris-Ma?
- Taken for Granite: Organic beings become crystalized when they make contact with Priz-Ma, allowing for easy absorption.
- Time Master: Priz-Ma can even reverse time!
- Tractor Beam: What it uses to absorb solid matter into its mass asides from physical contact.
Alien Carmilla Draculas
- First Appearance: Rout the NightVoiced by: Tetsuya Kaji
- Bat Out of Hell: His true form.
- Breath Weapon: Two actually; the first is a blinding mist, and the second is red energy bolts.
- Dead Person Impersonation: Draculas possesses the corpse of a deceased woman in order to avoid exposure to sunlight in daytime as well as MAT's notice. Of course, the heroes eventually catch on, forcing him to drop his disguise.
- Energy Absorption: Draculas' ability to drain the life force of others extends to Ultras, managing to set off Jack's Colour Timer prematurely after biting him down in the shoulders.
- Evil Is Not Well-Lit: Being a vampire, he's obviously nocturnal.
- Impaled with Extreme Prejudice: Just like the legends.
- Meaningful Name: Obviously, he's named after Count Dracula, but his species name, Alien Carmilla, is derived from the title character of a vampire novella.
- Our Vampires Are Different: First of all, he's an alien capable of possessing corpses to hide from sunlight. Second, he drinks life force rather than blood.
- Weakened by the Light: As a space vampire and all that.
- Would Hit a Girl: His entire scheme was to wipe out Earth's women, what did you think?
- First Appearance: Ultraman Dies at TwilightVoiced by: Masahiko Naruse
As the most dangerous of Ultraman Jack's foes, Alien Nackle has reappeared many times in the Ultra Series and his debut two-parter remains one of the most highly praised episodes of the franchise. Alien Nackle has played many roles in his reappearances, but almost all of them are no less villainous than the original.
- The Bad Guy Wins: One of the only villains in the Ultra Series to outright defeat the Ultra heroes and take over the world successfully. Of course, in Part 2, Jack comes back and gives him and Black King the much-deserved beating of their lives.
- Beware the Silly Ones: Sure, Nackle may look a little silly (polka dot skin?), but make no mistake, he really is one of Jack's most dangerous enemies!
- Brains and Brawn: The Brains to Black King's Brawn, as Nackle doesn't have much to contribute in melee combat, while Black King is basically a mindless mass of muscle.
- Breakout Villain: As the most iconic seijin in Return of Ultraman, Nackle has reappeared numerous times against many other Ultra heroes.
- Expy: Was meant to be one of Alien Guts in his debut, as seen with his Monster of the Week plot, dangerous cunning, and crucifixion of Jack. However, the two have become more distinct since then.
- Eye Beams: Alien Nackle doesn't have a lot in the "flashy powers" department beyond these.
- Hand Blast: His only other special combat power is to shoot similar bolts of energy from his palms.
- Jerkass: In almost all his appearances but especially his debut.
- Kick the Dog: Kills Aki and Ken in order to emotionally destroy Goh, but it wouldn't be his last wicked deed.
- Knight of Cerebus: As the most dangerous villain of the series, Nackle's episodes were definitely not as lighthearted as the rest, and his defeat would spawn a slew of alien invasions in his wake.
- Mind Control: Subjugates the entire Earth through a satellite dish that fires mind control waves.
- No Mouth: The glowing red thing beneath his eyes is the closest we get to one.
- Would Hit a Girl: Evidenced by his hands at the murder of Aki.
- First Appearance: Ultraman Dies at Twilight
Although not as iconic as his counterparts Red King and Gomora, Black King is possibly an even more formidable opponent than either, making him an incredibly popular monster. Thus Black King has reappeared numerous times in the Ultra Series, starting with Mega Monster Battle: Ultra Galaxy Legends.
- Brains and Brawn: The Brawn to Nackle's Brains, to the point where Nackle's incredible cunning and Black King's formidable strength effectively form a single frighteningly powerful opponent.
- Breakout Villain: Like Alien Nackle, Black King is an incredibly popular monster for being one of Jack's most lethal foes. They're still frequently teamed up with each other in modern series.
- Breath Weapon: Breathes a beam of intense fire called Hell Magma. He's also seen breathing white smoke as a getaway cover.
- The Dragon: He's not merely a pet or a bioweapon for Nackle, like most giant monsters are to evil aliens in the Ultra Series. However, All There in the Manual sources claim the Nackle species mass-produce armies of Black Kings.
- Dumb Muscle: Although incredibly strong, Black King's not terribly bright, hence the reason why he's often bossed around by an evil alien rather than seen as an independent monster.
- Everything's Better with Dinosaurs: Case in point, in Ultraman Ginga, his Spark Doll is mistaken for a dinosaur toy.
- Expy: Of Gomora and Red King. All three are brutish dinosaur-like monsters that have immense strength and superb toughness. Like Gomora, he's also able to defeat an Ultraman, while like Red King, he's not very bright.
- The Juggernaut: Almost nothing can scratch his flesh, and good luck even trying to surpass his strength.
- Off with His Head!: His fate.
- Super Strength: Do we really have to emphasize this again? This guy's like Red King on steroids.
- Tunnel King: Can move about underground to avoid notice.
- The Worf Effect: So strong, so tough, and so powerful that Jack was unable to beat him at all the first time (though it also had a lot to do with how depressed Goh was about the death of Ken and Aki).
- First Appearance: The 20th Century YetiVoiced by: Isao Yatsu
- An Ice Person: Naturally, he hails from a very frigid planet and seeks to freeze up Earth for conquest.
- Breath Weapon: Can breath freezing mist.
- Bigfoot, Sasquatch and Yeti: Is repeatedly mistaken for a yeti in the episode, even though he looks absolutely nothing like one.
- Dead Person Impersonation: In order to help spread news of his attacks, Varduck takes the form of one of the mountaineers he's killed.
- I'm Melting!: How Jack kills him.
- Spell My Name with an "S": Varduck or Bardak? It all depends on how you translate it.
- First Appearance: The Phantom Snow WomanVoiced by: Hiroyuki Yuyama
- An Ice Person: Like Alien Varduck before him, Alien Black's goal is to freeze Earth to make it ripe for takeover. He's also stated to have some minor ice-based powers, but we never see them.
- First Appearance: The Phantom Snow WomanPlayed by: Junko Arai (Yuki-onna form)
- An Ice Person: Obviously. Just look at its name!
- Breath Weapon: Breathes a very powerful, fast-working freezing mist.
- Hand Blast: Snowgon can fire the same super-freezing mist from its hands.
- Hero Killer: Albeit very briefly thanks to a Deus ex Machina, starting a minor trend of insignificant one-episode deaths for Ultra heroes.
- Hoist by His Own Petard: Jack destroys Snowgon by reflecting its freezing breath back at it with the Ultra Bracelet, which leads to...
- Literally Shattered Lives: Jack then pushes Snowgon over!
- Mix-and-Match Critters: Resembles a yeti mixed with a polar bear and a dragon.
- Super Strength: Strong enough to tear apart anybody iced up by its Breath Weapon into pieces.
- Voluntary Shapeshifting: Can transform into a Yuki Onna, though it can still use all its abilities.
- Yuki Onna: Inspired by the youkai. Its subtitle is even "Yuki-onna Monster".
Alien Baltan Jr.
- First Appearance: The Revenge of Alien Baltan Jr.Voiced by: Osamu Saka
- Art Evolution: Due to being a younger member of his species, Jr. is a golden brown in colour with a stouter appearance than the first and second Baltans from Ultraman.
- Avenging the Villain: The son of the first Alien Baltan seen in the original Ultraman.
- Phantom Zone: Baltan Jr. creates a shadow dimension inside the walls of buildings as part of his plan, allowing him and Billgamo to hide from MAT. Puddles of red liquid that cause whoever steps in them to be sucked into the shadow world allow for entry.
- Villain: Exit, Stage Left: After Ultraman Jack destroys Billgamo, Baltan Jr. flies off and Jack fires a Specium Ray, only for Baltan Jr. to vanish in a flash of light and leave his fate and the episode on a cliffhanger.
- First Appearance: The Revenge of Alien Baltan Jr.
- Blinded by the Light: Billgamo can fire blinding flashes of explosive light from its hands and antennae.
- Combining Mecha: Able to split into five parts, as the robot's torso is actually a building used by Baltan Jr. in his scheme.
- Death Ray: Fire one from the antennae on its forehead.
- Humongous Mecha: A giant robot constructed by Baltan Jr. to defeat Ultraman Jack.
- Spell My Name with an "S": There are one or two L's and/or M's depending on who you ask. Additionally, some may spell its name as Bilagammo or Builgamo.
- Spin Attack: One of Billgamo's primary abilities is to rotate its upper half at incredibly speeds.
- Tin-Can Robot: A very boxy design inspired by Ultraseven's Crazygon.
- First Appearance: The Monster That Stands on Mt. FujiVoiced by: Osamu Saka
- Synchronization: Stora bursts into flames and dies after Jack kills Paragon by tossing the monster into Mt. Fuji's lava-filled crater, suggesting this to be the case.
- First Appearance: The Monster That Stands on Mt. Fuji
- Barrier Warrior: Paragon is able to generate a force field in front of itself at will.
- Blow You Away: The weird wing-shaped projections on its shoulders can be flapped to create powerful winds.
- Disney Villain Death: Ultraman Jack sends Paragon tumbling into lava by blowing up the cliff its standing on.
- Kill It with Fire: Ultraman Jack defeats Paragon by knocking it into Mt. Fuji's lava-filled with crater, incinerating the monster.
- Master of Illusion: Probably one of the most powerful illusion-based opponents of the Ultra heroes. Paragon uses its ability to fool MAT into attacking villages and each other, cause cars to crash into each other, create duplicates of itself, and even make itself seem as big as Mt. Fuji.
- Pet Monstrosity: Of Alien Stora.
- Shock and Awe: Able to fire an electrifying bolt of energy from the glowing orb thingy above its shoulders.
- Teleport Spam: Which it uses to frustrate Ultraman Jack even further.
- First Appearance: Demon God Barks at the MoonVoiced by: Kentaro Kaji
- Applied Phlebotinum: His weapon of choice: the Grotescells, which are portrayed as a semi-vaporous chemical that enters hollow objects in order to bring them to life and transform them into kaiju. Killing Grotes is the only way to end turn the objects back to normal.
- Arm Cannon: The weird finger-shaped things on his fists are actually implanted organic machine guns that he can use in combat.
- Half the Man He Used to Be: His fate.
- Invisibility: By waving his hands over the blue jewel embedded on his forehead, Grotes can vanish in thin air.
- Weaponized Teleportation: Grotes can teleport beings or objects to wherever he pleases by firing bolts of energy from his hands,
- First Appearance: Demon God Barks at the Moon
- Expy: Of Daimajin, another samurai-deity-golem kaiju. Kodaigon's Boss Subtitles is even "Majin Monster".
- Golem: Something like that.
- The Juggernaut: Most attacks completely bounce off of Kodaigon's body, so the only way to turn the monster back into a statue is to kill Grotes.
- Playing with Fire: Kodaigon is able to place its hand together in order to shoot out jets of flame from them.
- Samurai: Certainly resembles the part, complete with a sword that it can materialize out of thin air for combat. The villagers also consider it their home's guardian deity.
- First Appearance: To the Starry Sky with Lovevoiced by: Yukiko Inoue (also human form actor)
- HeelFace Turn: Her romance with Kishida quickly leads to her betraying her people's invasion plans to Goh and MAT, as well as promising to help them destroy Granadas.
- Heroic Sacrifice: Because the only way to kill Granadas is for her to destroy herself, Centaurus is forced to kill herself in order to defeat the monster.
- Interspecies Romance: She dates Kishida while disguised as a human, which is what causes her to reform and help MAT against the Centaurus invasion.
- Love Redeems: If it wasn't for her romance with Kishida, Centaurus would have been yet another evil invader in the series' long consecutive line of them after Alien Nackle.
- Taking You with Me: She does this to Granadas by throwing herself with the monster off a cliff where they are both destroyed in a massive explosion caused by Centaurus.
- First Appearance: To the Starry Sky with Love
- Blade Below the Shoulder: Possesses scythe-like blade in place of hands, as well as feet.
- Breath Weapon: Spits organic missiles.
- Disney Villain Death: Centaurus throws herself with Granadas off a cliff, where a fiery explosion caused by the alien destroys both at the bottom.
- Eye Beams: Granadas can shoot bolts of light from its eyes that burst into blue flames upon impact.
- Technicolor Fire: Due to the phosphorescent properties of its Eye Beams, Granadas creates lots of blue fire when it causes destruction.
Alien Cygnus-61 Erika Shiratori
- First Appearance: Assassinate Hideki Goh!Played by: Junko Kawasaki
- Creepy Child: A mind-controlled little girl in white sent to murder a grown man. That is pretty creepy. However, she does befriend Jiro and turns out to be quite friendly once her mind-controlling headband is removed.
- Human Aliens: Or at the very least, we never see what she really looks like.
- First Appearance: Assassinate Hideki Goh!
- Breath Weapon: Breathes fire.
- Meaningful Name: Combination of "Robot" (see Robotic Reveal) and "Nezumi" (the Japanese word for ""rat").
- Poisonous Person: Robonez's fangs are coated with a deadly venom that paralyzes Ultraman Jack, affecting Goh for the rest of the episode.
- Prehensile Tail: Uses its tail to ensnare Jack and electrocute him.
- Robotic Reveal: Its skeleton turns out to be rather mechanical when Goh kills it, suggesting Robonez was a cyborg.
- Rodents of Unusual Size: It's a 35-meter tall rat kaiju!
- Shock and Awe: can channel electricity through its Prehensile Tail to shock foes.
- Stripped to the Bone: Jack destroys the monster at the beginning of the episode in this manner with the Ultra Bracelet.
- You Dirty Rat!: Alien Messie and Erika created Robonez by transforming a normal rat into a giant monster.
- First Appearance: Assassinate Hideki Goh!Voiced by: Isao Yatsu
- Kick the Dog: Mind controlling an innocent little alien girl is one thing, but did he really have to kill her father as well?! And to top it off, he disguises himself as a doctor to give Goh poison disguised as medicine to worsen Robonez's venom, and holds Erika hostage when the plan starts going south.
- Little Green Men: His true form, although he's not really little once he turns giant-sized to battle Ultraman Jack himself.
- Mind Control: That headband Eika wears? That's how he's controlling her.
- My Brain Is Big: His bulbous forehead, which can also fire laser beams.
- First Appearance: This One Blow Filled With AngerPlayed by: Isao Yatsu (voice), Takara Masayoshi (human form)
- Bitch in Sheep's Clothing: He disguises himself as a friendly old artist and pretends to bond with a buncyh of kids, and then when no ones looking, he beats up and injuries a boy and frames Goh for it.
- This Was His True Form: Like Zelan from earlier, Zoole only reveals his true form at the end of the episode.
- First Appearance: This One Blow Filled With Anger
- Battle Boomerang: Its weapons of choice, which are equipped in place of hands. They can be thrown over several city blocks and can slice through a skyscraper effortlessly.
- Breath Weapon: Breathes an explosive white gas.
- Everything's Better with Dinosaurs: Boomerang-handed alien dinosaurs!
- Half the Man He Used to Be: Immediately after getting decapitated, Red Killer's headless body splits apart.
- Hoist by His Own Petard: Jack defeats Red Killer by grabbing the monster's boomerangs and using them to slice off its head.
- Names to Run Away from Really Fast: Red Killer sounds an awful lot like what someone would call a notorious communist assassin, no?
- Off with His Head!: Its fate.
- Pet Monstrosity: To Alien Zoole.
- First Appearance: The Targeted Woman
- Clucking Funny: While not exactly humorous, Femigon is based on roosters.
- Breath Weapon: Breathes fire.
- Demonic Possession: Femigon's primary gimmick is that it possesses human women like Oka, forcing them to transform into Femigon whenever the entity wills it. In later series, it also means harming Femigon will harm the human its possessing.
- Energy Being: Femigon's natural form is a wisp-like creature made of fire, only becoming the chicken monster by possessing human women.
- Energy Absorption: Femigon consumes fire for sustenance, causing destruction in its chicken monster form to create its food source.
- Eye Beams: Femigon can shoot darts of fiery red energy from its eyes.
- Hitodama Light: Inspired by these. Its Boss Subtitles is even "Hitodama Monster".
- The Last of These Is Not Like the Others: As you might have noticed, ever since Nackle and Black King almost defeated Ultraman Jack, every single Monster of the Week has been connected to an alien invader in some way. Femigon is the sole exception.
- Playing with Fire: It's made of fire, it consumes fire, it breathes fire, and it grants those it possesses pyrokinesis. Do we really need to explain?
- Powers via Possession: Women possessed by Femigon gain the ability to set things on fire with their mind.
- First Appearance: I'm Taking the Earth!
- Big Eater: Yamentaranse's sole interest is food, which causes it to balloon to kaiju size over the course of the episode.
- Gentle Giant: A purely harmless creature, even when kaiju-sized, due to how lazy it is. So Ultraman Jack simply defeats the monster by throwing it into space.
- Lazy Bum: To such levels that it affects others with it. Already lazy people like Jiro become more energetic instead, but they also spread the monster's highly contagious laziness. Fortunately, sheer willpower can overcome the effect.
- Make My Monster Grow: Slowly increases it size over the episode from eating so much.
- Our Monsters Are Weird: A muppet-like creature with no visible feet that causes laziness...Definitely one of the goofier creatures in the show, but the episode it appears in is appropriately comedic.
- First Appearance: I'm Taking the Earth!Voiced by: Isao Yatsu
- Breath Weapon: Sasahillar can breathe an explosive yellow gas from his mouth.
- I'm Melting!: Dissolves into a green foam after getting hit by Ultraman Jack's Specium Ray.
- Spell My Name with an "S": Sasahillar or Sasahiller?
- Starfish Aliens: Although played by a man in a rubber suit, the best way to describe his design would be something akin to a bipedal manta ray.
- First Appearance: Space Warriors - Your Name is MATVoiced by: Fujio Murakami (good; also human form actor), Hironori Morimoto (evil; also human form actor)
- Archenemy: Of the Alien Ateria, whom they've been waging war with for millennia. However, the Ateria are never ever seen, nor do they ever interact with the characters in any way, so they really just serve as an excuse for the brothers to come to Earth.
- Breath Weapon: The Mystellars are able to spit organic missiles from their trunk-like mouths.
- Cain and Abel: The brothers are usually identified as the "Good" one and the "Evil" one. To elaborate, the Good Brother had come to Earth because he wanted to find a planet far away from the conflict that his homeworld had experienced for far too long and intended to simply live amongst the humans in peace, but the Evil Brother solely wanted to continue waging war and was perfectly willing to enslave Ultraman Jack and kill his own sibling and niece if it would help.
- Mind Control: The Evil Brother does this to MAT to make them attack Ultraman Jack when he refuses to join their cause, as well as capture his niece Emi to blackmail his brother.
- Spell My Name with an "S": Mystellar or Mysteler?
- First Appearance: Invitation from Hell
- Beneath the Earth: His species hails from thrity kilometers below the surface.
- Dishing Out Dirt: King Bockle is able to cause earthquakes by channeling certain waves or frequencies through his antennae.
- Mind Control: The antennae on King Bockle's forehead allow him to manipulate all sorts of waves and frequencies, which he can use to mind control humans.
- Our Monsters Are Weird: A green-skinned subterranean humanoid who has a white featureless head with two black slits for eyes, as well as two antennae growing from his shoulders...This guy easily has to rank among the weirdest-looking monsters in the Ultra Series.
- Poisonous Person: King Bockle can release a spray of toxic gas from his forehead.
- First Appearance: The Five Ultra PledgesVoiced by: Osamu Saka
Alien Bat has made a significant return in the Ultraman Zero movies and specials as one of Zero's chief enemies. For these appearances, he received a drastic and more intimidating redesign, and was changed from a run-of-the-mill invader to an Omnicidal Maniac who seeks to destroy the multiverse. However, he still maintains his habit of resurrecting the Ultra Series' most infamous kaiju to do his bidding.
- Breakout Villain: Although he's not quite as popular or frequently appearing as his fellow infamously ruthless alien foe of Jack, Alien Nackle, and is generally more of Ultraman Zero's enemy now these days, Alien Bat has still achieved this status to some extent.
- Hand Blast: Can fire laser bolts from his claws.
- Impaled with Extreme Prejudice: Ultraman Jack does it to him in the same manner that he did to Draculas earlier.
- Kick the Dog: He tries to weaken Goh for the battle against Zetton by kidnapping Jiro and Rumiko, as well as tormenting him with nightmares of being killed by Zetton.
- Necromancer: He has a habit of reviving monsters to do the fighting for him, especially powerful ones like Zetton, Red King, Galberos, Gan Q, and Bemstar. Justified as he doesn't have much to give out when it comes to straightforward the combat against the Ultras.
- First Appearance: The Five Ultra Pledges
- Art Evolution: Perhaps Art "Devolution" in this case. The low-quality suit used for the monster results in Zetton having a bulkier appearance, floppy antennae, a dirtier shade of black, and rectangular claws with holes in the fingertips (rather than the mitten-like hands usually seen on Zetton).
- Back from the Dead: Once again, this is the Zetton that killed the original Ultraman.
- The Dreaded: Alien Bat resurrected Zetton due to the monster's reputation as having killed the original Ultraman. Ultraman Jack actually forbids Hideki Goh from transforming when he learns that Zetton is the enemy!
- Hand Blast: This version of Zetton can spray a shower of explosive sparks from its hands.
- Lightning Bruiser: Whereas the original Zetton took lumbering, robotic strides, this version of Zetton zips about the battlefield quite a bit.
- Magnetism Manipulation: This version of Zetton can magnetize its body to pull Ultraman Jack towards it.
- Shock and Awe: This version of Zetton can electrocute enemies by grabbing them.