Evil Vs. Evil

This category refers to morally-dubious characters whose main enemies are themselves villains. Obviously, the story needs to have more than one villain (or even a multi-being or dissociative villain with two evil counterparts) for this to be possible. Many extremely dark works, such as Warhammer 40,000, base their main conflicts around this principle, and nearly all Protagonists are portrayed mainly fighting individuals who are either similar to or clearly even worse than they are. However, not every villain who has ever fought another villain should go here. Villains only belong if this applies to most or all of their activities and is a significant aspect of their character and if they are seen as "Heroes" in their setting due to the extreme levels of wickedness committed by their enemies. Some of these villains are also known as "Enemy of a Villain".

Good examples of this include Joseph Stalin and Adolf Hitler, Vegeta and Frieza, Slade and Trigon, Freddy Krueger and Jason Voorhees, Mr. Krabs and Plankton (more specifically after the first movie), Kratos and Zeus, Megatron and Starscream, Fliqpy and Tiger General, Tom Cat and Jerry Mouse, Ryuga and Rago, Spectra Phantom and King Zenoheld, Wario and Bowser, Kazuya Mishima and Heihachi Mishima, Xenomorphs and Predators, Tony Soprano and Phil Leotardo, Trevor Philips and Devin Weston, Megamind and Tighten, Rick Sanchez and Rick Prime, Risky Boots and Pirate Master, Harley Quinn and Joker, Dan and Travis Touchdown, The Beast and Gaston LeGume, Kash D. Langford and Daniel Kon, Team Aqua and Team Magma, Mal and Uma, Walter White and Gus Fring, Prince Olympius and Diabolico, Gumball Watterson and Rob, and Tomura Shigaraki and Re-Destro. Void 4 is an example, since he is a noble demon bent on destroying Black Hole and tyrants. Maleficient, Queen Ingrith and King Stefan fit this trope for most of Maleficent (and its sequel), as all three are villains who are fighting against each other. Alejandro and Heather from the Total Drama franchise also fall under this category, as they both have a rivalry during their time in the competition. For the third season of 13 Reasons Why, Bryce Walker, Monty de la Cruz, Zach Dempsey, Marcus Cole, Clay Jensen, Justin Foley, and the rest of The Bakers Dozen at Liberty High School are all examples of this.

Even villainous protagonists can qualify if they are (or occasionally) rivals with a villain. Good Examples: Peter Griffin and Carter Pewterschidmt, Felonious Gru and Vector Perkins, Darth Vader and Emperor Palpatine, Ryuga and Rago, Megamind and Tighten, Jim Carrey Grinch and Mayor Augustus Maywho, Venom (Sony's Spider-Man Universe), and Riot (Sony's Spider-Man Universe), Mr. Krabs and Plankton, Heinz Doofenshmirtz and Aloyse von Roddenstein, and Trevor Philips and Steve Haines.

NOTE: Sometimes after an Evil Vs. Evil battle has ended and a less evil villain defeated the true evildoer, the less evil villain might possibly reform and become a hero or maybe an anti-villain if they wish, in which case they will NOT qualify as Karma Houdini. In such cases, they involve a more sympathetic villain going up against someone much worse. Although, there are cases of Pure Evil villains who can viciously dispose another villain who is not Pure Evil (if able), and in rarer cases, a Pure Evil villain will take on against another Pure Evil villain so this category counts as such. See Pure Evil Vs. Pure Evil.