Every Power Rangers series has its own assortment of wild villains.
Live-Action Television
Zordon Era- Mighty Morphin' Power Rangers: The Big Bad Duumvirate of Rita Repulsa and Lord Zedd.
- Season One: Rita Repulsa, an evil sorceress and the one sending monsters to conquer Earth, as well as the one who makes them GROW after they're defeated.
- Season Two starts with Rita's master Lord Zedd showing up to oust her for her repeated failures and take over the invasion of Earth himself. Rita returns near the end of the season, using a love potion to marry Zedd.
- Season Three: Rita and Zedd, now a Big Bad Duumvirate jointly leading the villains, until Rita's father Master Vile arrives near the end of the season and supplants them as the biggest threat to the Rangers.
- Alien Rangers: Master Vile quickly gives up in the two-part premiere and cedes the position back to Zedd and Rita, who proceed to destroy first the Power Coins and then the Command Center after summoning Hydro Hog to distract the Alien Rangers.
- Power Rangers Zeo: King Mondo, leader of the invading Machine Empire, at first. After Mondo gets destroyed by the Rangers, Rita and Zedd take the role when they use Louie Kaboom to take over the Machine Empire, only for Kaboom to go rogue. Louie Kaboom is then quickly overthrown by Prince Gasket and Princess Archerina, who seize control of the Machine Empire for the remainder of the series until Mondo is rebuilt and resumes command in the final few episodes.
- Power Rangers Turbo: Divatox, a space pirate who seeks to release and marry the demon Maligore in the movie, and who spends the series causing petty chaos in retaliation for his death.
- Power Rangers in Space: Astronema, the leading commander of the United Alliance of Evil sent to fight the Space Rangers. She's subordinate to Dark Specter, the leader of the United Alliance of Evil and the Greater-Scope Villain behind every previous villain, but never gets personally involved for most of the series. After Dark Specter dies in the first half of the finale, Astronema takes over as the Grand Monarch of Evil in the second half.
Post-Zordon Saban Era
- Power Rangers Lost Galaxy: Scorpius, the leader of the aliens sieging the Terra Venture, until he is killed halfway through and succeeded by his daughter Trakeena. There's also Deviot, who spends most of the series plotting against them and to take Scorpius' Cocoon for himself, and Captain Mutiny as an Arc Villain. In the end Trakeena outlives both of them and becomes the final boss, though Deviot's influence still lingers after his personality gets absorbed into Trakeena and makes her more ruthless and sadistic.
- Power Rangers Lightspeed Rescue: Bansheera, the queen of the demons. Although as she's imprisoned for most of the series her Dragon, Diabolico, and son, Prince Olympius, lead the charge until Bansheera regains physical form.
- Power Rangers Time Force: Ransik is the leader of the mutant criminals who travels to the past to wreak havoc. His robot servant Frax is a secondary threat, wanting revenge after Ransik almost killed him and forced him to turn himself into a robot to survive. Unfortunately, Ransik manages to get him back under his control by the finale, and his personality is wiped in the reprogramming.
- Power Rangers Wild Force: Master Org, actually the human Dr. Viktor Adler, who consumed the remains of the original Master Org and assumed his identity to lead the Orgs to take over the world. He's killed and briefly usurped by Mandilok once the truth comes out, only for the true Master Org to emerge from him and retake his throne.
Disney Era
- Power Rangers Ninja Storm: Lothor, the leader of the alien ninjas and Cam's Evil Uncle. He's unusually comedic, even for a Power Rangers Big Bad, but still proves himself dangerous with his gambit to open the Abyss of Evil and unleash all of his defeated monsters and generals.
- Power Rangers: Dino Thunder: Mesogog, Anton Mercer's evil split-personality, who wants to destroy humanity and restore earth to the era of the dinosaurs. Zeltrax and Elsa are Co-Dragons, and while the former betrays him halfway through Mesogog remains the greater threat.
- Power Rangers S.P.D.: Emperor Gruumm is the ruler of the Troobian Empire and Cruger's Arch-Enemy, with his weapons-supplier Broodwing becoming a secondary threat when he strikes out on his own after Grumm doesn't pay him one too many times. In the finale it's revealed Gruumm was serving Omni all along, with his end plan being to build him the perfect body.
- Power Rangers Mystic Force: Octomus is The Master of the underworld and the Morlocks, but due to being sealed away he has to rely on Arc Villains to try and free him: Morticon, Imperious (who intends to betray him), and the Ten Terrors lead by Sculpin.
- Power Rangers Operation Overdrive: A Big Bad Ensemble after the Corona Aurora: the two brothers Flurious and Moltor; the cyborg warrior Kamdor and his assistant Miratrix; and the Fearcats, Mig and Benglo. Flurious outlives them all and serves as the Final Boss, killing his brother himself and assembling the Corona Aurora. The anniversary Two-Part Episode "Once A Ranger" briefly features Thrax, the son of Rita and Zedd, who takes control of the Big Bad Ensemble and forms them into a Legion of Doom before being slain by the Sentinel Knight.
- Power Rangers Jungle Fury: Dai Shi, the dragonic leader of the Dai Shi clan, who possesses expelled Pai Zhua student Jarrod and works to regain his former power throughout the series. He's briefly overthrown by Grizzaka, but quickly takes back control from the Overlords with the help of the Phantom Beasts.
- Power Rangers RPM: The Venjix computer virus created by Dr. K, which has already wiped out a majority of the human population. While initially content to just send monsters to attack one of the last remaining cities, Corinth, Venjix gradually takes greater action personally and builds himself a series of increasingly more powerful bodies. He nearly succeeds in wiping out Corinth in the finale by turning many of its inhabitants into robots over the course of the series, including Dillon.
- Power Rangers Samurai: Master Xandred is the lord of the Nighloks, though he's content to be an Orcus on His Throne and let his minions throw monsters at the Rangers. As such, each season has a more prominent secondary threat.
- Season One: Deker is a half-Nighlok warrior who wants to fight Jayden in an "Ultimate Duel" that will end his immortality, serving as The Heavy and Final Boss of the season as the Rangers' most recurring opponent.
- Season Two: Serrator, the former Nighlok king who cursed Deker and Dayu, is introduced as a Dragon with an Agenda for Xandred with his own plan to crack the world in half. Unfortunately for him, Xandred is still a much more powerful physical threat who reclaims the position of main antagonist once Serrator and Deker are killed.
- Power Rangers Megaforce: Vrak is the younger prince of the Armada and The Heavy who leads various villainous factions into conflict with the Rangers, with his father Emperor Mavro as the Greater-Scope Villain behind the invasions.
- Season One: Admiral Malkor is the leader of the Warstar to whom Vrak serves as the Dragon-in-Chief. Vrak outlasts his superior after the Admiral becomes a Disc-One Final Boss, taking over the efforts at conquest with his own robotic minions.
- Season Two: Prince Vekar, Vrak's brother, is The Heavy who begins harassing the Rangers with the rest of the Armada, but is too incompetent to be considered a true threat without his family's resources. After Vekar becomes another Disc-One Final Boss, Vrak resurfaces with a plan to outright destroy earth. Emperor Mavro makes his introduction as the Final Boss afterwards, launching one final invasion to avenge his sons.
- Power Rangers Dino Charge: Sledge is the leader of the alien bounty hunters after the Energems, who sends his prisoners to steal them from the Rangers. Heckyl and his Literal Split Personality, Snide, are his most powerful prisoners who become The Heavy in the second season after Sledge's apparent death, distracting the Rangers while Sledge prepares his master plan. Lord Arcanon, Sledge's employer and Snide's creator, briefly ousts Heckyl from command only to wind up a Disc-One Final Boss when Sledge turns on him, with Heckyl pulling a Heel–Face Turn after being separated from his evil counterpart.
- Power Rangers Ninja Steel:
- Season One: Galvanax uses his alien gladiator show to find warriors he can send to earth to steal the Ninja Nexus Prism, with his servant Madame Odius constantly plotting to overthrow him in the background.
- Season Two: Madame Odius takes over the Galaxy Warriors show after Galvanax's death, backstabbing contestants to steal their power as part of a plan to fuse with the Nexus Prism.
Hasbro Era
- Power Rangers Beast Morphers: The rogue computer virus Evox creates the Blaze and Roxy Avatars as his Co-Dragons, sending them to steal Morph-X so he can escape the Cyber Dimension and access the Morphing Grid. Season 2 sees him survive his apparent death and possess Mayor Daniels, before using Ryjack's Reanimizer to resurrect deceased villains (such as Goldar and Sledge's crew). The finale reveals he's a reincarnated Venjix, having survived the end of RPM and been given a new form after his code was mixed with Morph-X and snake DNA by a young Nate.
- Power Rangers Dino Fury: Void Knight a mysterious villain who wants to find an energy source to charge the sporix machine which will allow him to bring back to life his wife.
- Void Knight is Demoted to Dragon by his wife Void Queen who wants to destroy humanity to avenge for her dead child.
- Power Rangers Cosmic Fury (warning — Late-Arrival Spoiler for Dino Fury): Lord Zedd comes back from the dead in Dino Fury season one, is an Arc Villain in season two, and becomes the main villain of Cosmic.
Boom Studios! Comics
- Mighty Morphin' Power Rangersnote :
- The initial arc has Rita Repulsa, the master or creator of pretty much every evil alien and monster encountered. One arc also introduces Lord Drakkon, an alternate universe of Tommy who stayed evil and overthrew Rita, proceeding to take over his world. Finster takes over in the time between Drakkon's first defeat and Shattered Grid.
- Mighty Morphin' Power Rangers: Shattered Grid: Lord Drakkon, having escaped his imprisonment and initiated an invasion of the multiverse, culminating in him destroying everything and remaking reality with him as its God. The Ranger Slayer, the World of the Coinless' Kimberly, serves as his Brainwashed and Crazy Dragon, time-traveling to before the Rangers met Drakkon and being freed from his control.
- Beyond the Grid: The Praetor, a Morphin Master and leader of the Crimson Raiders, who exiled his world off from the multiverse in order to save it before devolving into nihilism and omnicidalness.
- Necessary Evil: A Big Bad Ensemble between Lord Zedd and the Omega Water Ranger Kiya. The latter goes off the deep end in a desire to kill Tommy so he doesn't become Drakkon, recruiting and empowering an army of criminals to do so. The former, after the climax, returns empowered and creates a team of Dark Rangers.
- Unlimited Power: A Big Bad Ensemble between Lord Zedd, having gained a power boost from the Chaos Energy of the new Green Ranger; and Zordon's former Eltarian superior Zartus, using the Empyreal to wipe out worlds.
- Power Rangers Unlimited: Heir to Darkness: Astronema is a Villain Protagonist, being trained by Ecliptor to fight Darkonda's apprentice Dee for the right to be Dark Specter's heir.
- Power Rangers Unlimited: Edge of Darkness: Master Vile, seeking the young Rita to use as a vessel to summon Dark Specter.
- Power Rangers: Ranger Slayer: The resurrected Rita from the World of the Coinless.
- Power Rangers: Drakkon New Dawn: Eclipta, a representative of Dark Specter who Drakkon arranged to invade should he be dethroned.
- Mighty Morphin' Power Rangers: Pink: Goldar chases down Kimberly for revenge, but begrudgingly pulls an Enemy Mine with her when the Monster of the Week he brought along, Verto, betrays him.
- Power Rangers: Soul of the Dragon: The Witch, Scorpina, who serves as The Heavy to Lokar the Terrible.
- Power Rangers: The Psycho Path: Psycho Green, the former Super Sonic Ranger Trek.
- Power Rangers: Sins of the Future: Frix, a copy of Frax that's disrupting time by trying to prevent Ransik's Start of Darkness. Black Time Force Ranger Cyra Drake is initially the villain wanting revenge on Jen for Alex's death and revival, but quickly comes to her senses.
- Justice League/Mighty Morphin' Power Rangers: A Big Bad Duumvirate between Lord Zedd and Brainiac, the two allying to shrink and steal Angel Grove.
- Mighty Morphin Power Rangers/Teenage Mutant Ninja Turtles: A Big Bad Duumvirate between the Shredder and Rita, the former wanting control of the Dragonzord and the latter tricking the Shredder into giving her an audience with the Kraang.
Movies
- Mighty Morphin Power Rangers: The Movie: Ivan Ooze.
- Power Rangers (2017): Rita Repulsa, the former Green Ranger.
Other
- Power Rangers Hyperforce: The Alliance Leader, Thrax, who's actually The Dragon to Mr. Ashford.
