An Archenemy is the main enemy of the protagonist. The reason why the particular villain stands out more than the rest varies; they may be the hero's strongest enemy, be the complete antithesis to the hero, have strong connections with their hero's past, pose the greatest threat, or may be the most recurring villain like the Big Bad or the Right-Hand enforcer or even the Rival.

This is not to be confused with the Big Bad, who is the villain responsible for the conflict in the story, or The Heavy, who is the most proactive villain in the story. The Archenemy is simply the villain that the protagonist has the most personal opposition towards. For stories with multiple main heroes and villains, there may be multiple archenemies if each hero shares an antithesis on the villains side. In rare cases such as Evil Vs. Evil scenarios, two villains may be archenemies of each other.

Examples include The Joker from the Batman comics, Lex Luthor from the Superman comics, Circe from the Wonder Woman comics, Norman Osborn/Green Goblin from the Spider-Man comics, Red Skull from the Captain America comics, Doctor Doom from The Fanastic Four comics, Mandarin from the Iron Man comics, Lord Voldemort from Harry Potter, Violator from the Spawn comics, Agent Smith from The Matrix trilogy, The Leader from The Hulk comics, Ghostface from the Scream series, Jafar from Aladdin, Hades from Hercules King Ghidorah from the Godzilla film franchise, Gyaos from the Gamera film series, Cecil Clayton from Tarzan, Bowser from the Mario series, Dr. Eggman from the Sonic the Hedgehog series, Nigel from Rio, and Sephiroth from Final Fantasy VII and Revolver Ocelot from the Metal Gear Solid series, William Afton from the Five Nights at Freddy's franchise, Rita Repulsa from Power Rangers, Pete from Mickey Mouse and Elmer Fudd from Bugs Bunny. For an anime/manga example, Char Aznable from Mobile Suit Gundam, Frieza from Dragon Ball and Tomura Shigaraki from My Hero Academia.