James BurtonThe hero of Gradius 1, Nemesis 2, Gradius Rebirth. He is a Wreekian, just like Dr. Venom. After defeating Venom in Nemesis 2, James becomes Emperor Lars 18th. He passes away in year 6718, but that doesn't stop Dr. Venom from going to the past and kidnapping a three-year old James. Thank goodness David Burton, a descendant of James, saved the boy from Venom.
- Ace Pilot: He pilots the Vic Viper into at least three victories against the Bacterian armadas, Dr. Venom, and Bacterion.
- Arch-Enemy: Dr. Venom is this for James in two of the games, sending him out on no less than three deployments while Venom's staging a coup in Gradius ReBirth, becoming the boss of Nemesis 2 that James has to confront, and then kidnapping a toddler James in Nemesis 3.
- Human Alien: James looks like a human, but he is a Wreekian.
- Recurring Character: Is the Vic Viper pilot in three of the Gradius games, including the Grand Premiere installment and the last major game to be made as of 2016.
David BurtonThe hero of Nemesis 3. A descendant of the late James Burton, David repels Bacterian forces and discovers the Bacterians going back in time to change history. David saves a three-year old James Burton from the Bacterians and frees the Bacterian controlled planets.
- Ace Pilot: Just like his ancestor. He has to be in order to pilot the Vic Viper.
- Human Alien: Since James was a Wreekian, David has DNA of that race.
Eddie EvansOne of the protagonists of the Salamander OVA series. He gets manipulated by Paula, a Bacterian disguised as a human, into destroying the Bacterian repellent: the Moai Statue. Eddie redeems himself by sacrificing himself (by flying into the mouth dragon named Salamander) to save Gradius.
- Nice Job Breaking It, Hero!: Nice Job destroying the Moai statue, Eddie. Now the Bacterians will invade Gradius.
- Heroic Sacrifice: Destroys Salamander at the cost of his life.
- Redemption Equals Death: Eddie cocks up by destroying the statue, and it takes his death to correct it.
- Unwitting Pawn: Paula plays him into destroying the Moai Statue to allow the Bacterians to invade.
StephanieOne of the Protagonists of the Salamander OVA series. In the second Salamander OVA, she had to destroy her own father (who was kidnapped and turned into a Cyber Brain by the Bacterians). In the third, she gets kidnapped by the Bacterians and almost got become a cyber brain just like her father, but gets saved in time by Dan and Lord British.
Lord BritishOne of the Protagonists of the game Salamander and the Salamander OVA series. He is the ruler of planet Latis. His personality isn't very detailed in the games, but in the OVA series, he's a Jerkass.
- Royals Who Actually Do Something: Pilots his own super-fighter and takes the fight to the enemy in Salamander and Solar Assault.
BacterionBacterion, the god of destruction. The creator of the entire Bacterian Empire, Bacterion always tries to invade Gradius, home of the Vic Viper, the ship that always defeats him.
- Big Bad: The master and creator of the entire Bacterian Empire, who are the threats that Gradius is forced to defend itself against.
- Brain in a Jar: Sometimes.
- Evolved into a Planet: In Gradius III. Or maybe he have always been this way.
- Eldritch Abomination: Much like Gofer, a head with an exposed brain in a mess of laughing faces.
- Evil Is Visceral: His exposed brain is shown pulsing, and he is in a sea of organic-looking material.
- Final Boss: Bacterion is definitely the last enemy of Gradius III, but whether or not it was him as the brain in the original is up for debate.
- God of Evil: Check his quote.
- Hive Mind: Appears as this if the Vic Viper is able to reach him in Gradius 3; he controls all the Bacterian organisms.
- Recurring Character: He's the primary Big Bad of the Gradius franchise.
- The Emperor: The original Bacterian Emperor that rules an elite fleet of warships.
- Spell My Name with an "S": Bacterion or Bacterian?
- The Virus: Bacterion's strategy of conquering planets; Bacterion multiplies, then Bacterion use psychic controlling beings called Cyber Brains (for example, Venom and Gofer), or Bacterion uses his psychic powers to control those the duplicate cells and make them into fighter ships and monsters, called Bacterians. Combined with the intelligence of the Cyber Brains (or Bacterion), the Bacterians conquer planets into transform into whatever they like. If the Cyber Brains or Bacterion get blown up, at least the pieces would grow into more Cyber Brains, making the Bacterion Empire stronger.
- Zero-Effort Boss: He's notable for being one of the few final bosses (and the only main series one) to actually fire back! Unfortunately for him, his shots are slow and so easily avoided that he still qualifies as this (getting hit by one of these does send you to a sub-level that you have to fight your way through to get back to Bacterion on at least the arcade version of III).
GoferThe Big Bad of Gradius II and IV.
- The Dragon: Lampshaded by Gofer himself: "I am just a small portion of the empire Bacterion!"
- Dragon Ascendant: Replaces Bacterion as the Bacterian Emperor in II and IV and leads the charge against Gradius and the Vic Viper in his stead.
- Eldritch Abomination: A skinless head in a mess of organic tissue.
- Evil Is Visceral: His brain is exposed, and so are the muscles in his face.
- Final Boss: Is this for II and IV.
- Hive Mind: Gofer's one of the beings that can control the entire Bacterian Empire.
- My Death Is Just the Beginning: Gofer in Gradius IV states that he will be reborn in every single piece of Gofer's body. Fridge Logic would make his last words more of a warning than just mere words.
- Recurring Character: The Final Boss of two of the Gradius games.
- Was Once a Man: Until Bacterion turned Gofer into a giant skinless head.
- Zero-Effort Boss: In all arcade versions of the mainline games, Gofer doesn't attack when the Vic Viper reaches him; all one has to do is shoot the tendrills holding his head to the ceiling. In the NES port of II, he does spit out ballistics, and one of the sub-games does have him as a standard boss.
Zelos ForceThis Bacterian is a red gigantic eye created as a Living Weapon by the forces of Bacterion to transform planet Latis, a neighboring planet, into Bacterian territory.
- Degraded Boss: Zelos Force went from final boss to boss to a regular Mook in following games such as Gradius V. Still, an Elite Mook.
- Eldritch Abomination: The eye has a fiery glow around it and pulsing veins.
- Evil Is Visceral: A giant eye with veins is what the Zelos Force creatures look like
- Eye Scream: A big eye, and in his first game, you have to shoot said eye.
- Final Boss: Of arcade Salamander.
- Living Relic: In Gradius Neo and Gradius Neo Imperial, the Bacterian Empire doesn't exist anymore. All that's left is the Bacterians' technology, the Crystal Moai, and some wild Zelos Forces.
- Living Weapon: An eyeball that is a Bacterian weapon.
- Recurring Character: Appears as a Final Boss and then reappears in the first stage of Gradius V as an Elite Mook blocking the Vic Viper's path.
- Red Eyes, Take Warning: Zelos Force is a red eye.
- The Virus: That's what Zelos Force is designed for.
- Zero-Effort Boss: Averted; this last boss requires some input to survive because it comes in behind you, plus the base will try to shut you in.
PaulaA female Bacterian who is the Big Bad of the Salamander OVA series.
Life Force/Zelos(Not to be confused with the other Zelos)A Planet Eater that eats planets. Usually, you have to destroy him from the inside.
- Big Bad: Of the game Life Force.
- Eldritch Abomination
- Evil Is Visceral
- Genius Loci: Or so it seems to be at the ending of NES Life Force.
- Planet Eater
- Covers Always Lie: ...maybe. One would assume Zelos, based on the description, to be the flaming dragon depicted on the cover of the game, whose mouth is the size of a few planets in front of it. However, the same cover first originated with the arcade Salamander, the plot of which did not involve a planet eater.
Big Core SeriesA series of large Bacterian Warships that mostly serve as the bosses of the Gradius series. So far, there are Big Cores MK I, II, III, IV, and many variants.
- Ace Custom: Big Core MK I has two notable Ace Custom variations.
- Big Core Rev.1.2 in V, equipped with a ring of laser ring-spamming turrets AND planet-piercing laser cannons.
- Big Core Custom in NEO Imperial has Area Napalm, a multidirectional detonator. The player controls this Big Core trying to escape Lars Empire. Unfortunately, it has been destroyed by Gradius Union's forces.
- Degraded Boss: Big Core MK I went from a boss to an Elite Mook.
- Subverted, the heavily-modified version of Big Core MK I (which comes with more weaponry) appears as the first boss in Gradius V.
- Recurring Boss: At least one Big Core MK I of some sort will appear as a boss enemy in any game called Gradius. The first had nothing but Big Cores until the last two stages.
Dr. VenomThe Big Bad of Nemesis 2, 3, Gradius ReBirth and V. He constantly tries to destroy Gradius for using his people, who became an endangered species thanks to a future version of Venom and Gofer, only for their ESP powers.
- Arch-Enemy: Venom is this to James Burton, the original Vic Viper pilot, since he sends Burton out on several runs against a rogue Bacterian sector while he attempts a coup. Burton realizes this and has Venom imprisoned, but he escapes and becomes one of the main minds of the Bacterians, going up against James in Nemesis 2 and then trying to kidnap him as a child in Nemesis 3.
- Because Destiny Says So: The Latisian prophecy in Salamander MSX states that a devil with green skin and five eyes will cause two catastrophes. Guess who's the devil.
- The Dragon
- Eldritch Abomination: Venom was partly one in Nemesis 2 and 3 due to being transformed by the Bacterians, but he became a full Eldritch Abomination in Gradius V.
- Dragon Ascendant: Is one of the latest minds to take control of the Bacterians and lead them as a brain in an attempt to lay waste to Gradius.
- Evil Is Visceral: In Gradius V.
- Eye Scream: When you see him in Gradius V, he's just a brain with stationary eyes, and you have to shoot his eyes out to destroy him.
- Face–Heel Turn: Once the Director General of the Space Science Agency and, at least according to the events of Gradius ReBirth, was the head creator of the Vic Viper. But after the events of the prequel ReBirth (where Vic Viper pilot James Burton and the Gradian Empire wised on to Venom planning a coup of the planet), he left the agency and joined the Bacterians to attack the planet Gradius.
- Final Boss: In the mainline series, his brain is the last target of Gradius V. He's also the last boss in Nemesis II, but this one puts Venom behind the wheel of a Big Core machine.
- Go for the Eye: When you meet his brain in V, the target you are shooting at are his eyes; destroying them destroys him.
- Hive Mind: At some point, he becomes a Bacterian Emperor brain much like Bacterion and Gofer and attacks Gradius himself with the Bacterian Empire at his command in Gradius V.
- Human Alien: Started off this way. After an accidental exposure to radiation, he gained a much more alien appearance. Even later after this, he defected to the Bacterions and his physiology was altered, giving him the three extra eyes mentioned in Salamander and a more muscular build. Even later after this, he became nothing but a giant Brain in a Jar.
- Kill All Humans: His goal in V; his quote makes that very clear, since he is now a Bacterian Hive Mind.
- Recurring Character: Appears as a major antagonist in a handful of the games.
- Spikes of Villainy: His page image shows him in a dress with a major spike motif.
- Was Once a Man: Venom became a cyborg in Nemesis II but was still a Wreek. Now all that left of him is a Bacterian Hive Mind. According to the Gradius II bible, he once appeared just as human as the Burtons, but his appearance was caused by accidental exposure to some form of radiation.
- Zero-Effort Boss: As usual, once you're face to eye with his eyes, all you have to do is shoot them. This is not the case in Nemesis II, where he's piloting a Big Core ship and is attached to an actual boss fight.
Doom"I'm going to scare you like you've NEVER been scared before!" .
The Big Bad of Salamander 2. He was the most recent leader of the Salamander force, an elite Bacterian army that was previously led by Zelos Force and Venom. He only appeared in Salamander 2.
- Bullet Hell: He not only puts up a fight, but throws a bunch of bullets and discs at you.
- Final Boss: Of Salamander 2, and it's a full-blown boss fight instead of a Zero-Effort Boss.
- Humanoid Abomination
- Spell My Name with an "S": Doom's name is often confused with Giga, a boss from Life Force and the Famicom port of Gradius II in the form of a giant skull, due to his Leitmotif being titled "Giga's Rage."
- Taking You with Me: Says he'll take you with him to Hell when you destroy him; he fails, or course.
- Zero-Effort Boss: Averted. He is one of the few Gradius Final Bosses to put up an actual fight.