This is a list of some of the major foes of the Marvel Comics superhero team, the X-Men. This list is not comprehensive.

• The Brood
• Dire Wraiths
• Kree
• The Phalanx
• Quists
• Shi'Ar
• Siris
• Sirius
• Skrulls

• Supreme Pontiff (Leader)
• General Vicar
• Mister Clean

• Graydon Creed (Founder)
• Donovan Zane (successor)
• Bastion
• Checks
• Grinder
• Hanratty
• Jumbo
• W. C. Taylor

• Simon Trask (Founder, brother of Bolivar Trask)
• Eli Garibaldi
• Joelle Guthrie - Quit
• Tim Preacher - Quit
• Lieutenant Commander Coral Trent
• Commander Jared McGee
• Sean Lockwood
• Hound
• The Razors - Robots with techno-organic armor. They were later found and utilized by the Cabots against the Guthries and the X-Men
• The Shepherds - Robots incorporating Nimrod technology.

• William Stryker (Founder of Purifiers)
• Donald Pierce (Founder of Reavers)
• Graydon Creed (Founder of Friends of Humanity)
• Cameron Hodge (Founder of Right)
• Bolivar Trask (Creator of Sentinels)
• Stephen Lang (Manufacturer of Sentinels)
• Leper Queen (Founder of Sapien League)
• Matthew Risman (Successor of Stryker)
• Bastion
• Nimrod
• Eli Bard
• Lady Deathstrike

Mutant-hating cyborgs and street punks, led by Donald Pierce.

• Cameron Hodge (Founder)

• Leper Queen (Founder)

• Bolivar Trask (Creator of Sentinels)
• Steven Lang (Manufacturer of Sentinels)
• Lawrence Trask
• Master Mold
• Nimrod
• Bastion (Fusion of Master Mold and Nimrod)
• Omega Sentinel

• John Sublime (Founder)

The Neo are an offshoot of the mutant genome, that lived in seclusion from the rest of the world.

According to Azazel, they are all that remain of an ancient clan of mutants with vast powers and demonic looks.

A band of mutant mercenaries who have been hired by Apocalypse, A.I.M., and other criminals.

The descendants of Apocalypse. They first appeared in Apocalypse vs Dracula #1. While Blink and Chamber are descendants of Apocalypse, neither is considered a member of the Clan.

• Frederick Slade
• Hamilton Slade
• Jack Starsmore
• Kabar Brashir
• Margaret Slade
• Ozymandias

The immortal villain Apocalypse uses these mutants to try to force his "survival of the fittest" ideals on humanity.

• Death
  • Archangel
  • Caliban
  • Gambit
  • Wolverine
• Famine
  • Ahab
  • Autumn Rolfson
  • Sunfire
• Pestilence
  • Caliban
  • Plague
  • Polaris
• War
  • Abraham Kieros
  • Deathbird
  • Gazer
  • Hulk

A group of seemingly ageless mutants, each with their own schemes and agendas.

A powerful organization led by the Mutant Master with the goal of world-domination.

A team of federal agents which was established as a superhero team directly accountable to the US government. The team was formed from former members of the Brotherhood of Evil Mutants's second incarnation, but almost immediately began taking on new recruits.

Due to the long-standing and secretive nature of the organization, not all of its members are known. The listed members are all part of the Inner Circle, also known as the Lords Cardinal. The non-Inner Circle members include many wealthy or politically connected men and women of the Marvel Universe like Tony Stark and Norman Osborn and are generally unaware and/or uninvolved with the Club's illegal activities.

Young counterparts to the New Mutants, under Emma Frost's tutelage.

• Bedlam
• Feral
• King Bedlam
• Magma
• Paradigm
• Switch
• Tarot

The Acolytes are a group of mutant fanatics who believe that mutants are destined to conquer and destroy normal humanity.

Several groups of terrorists have used this name.

• Mister Sinister

A gang of mutant thugs who work for Mister Sinister. Vertigo was a member of this team on the 1990s X-Men cartoon.

Beings from a bizarre pocket of time who claim to be neither human nor mutant.

• Aguja
• Cadena
• Fuego
• Perro
• Sangre
• Serafina

This group was referred to as the Hellions only in promotional material, not in the actual comics.

An offshoot of the Morlocks, who blame the X-Men for their plight.

Mutant terrorists organized by Stryfe.

A group of mutant enforcers for the regime of Genosha.

• Hawkshaw
• Punchout
• Pipeline
• Wipeout

Formerly an incarnation of the Brotherhood of Evil Mutants.

• Burner
• Lifter
• Mentallo
• Mist Mistress
• Paralyzer
• Peepers
• Quill
• Rust
• Slither

Asian mercenaries including mutants, a cyborg, and a Sorcerer

Primitive humans genetically altered by Magneto.

• Chimera
• Martinique Jason
• Lady Deathstrike
• Lady Mastermind
• Psylocke
• Red Queen
• Spiral

Amoral thrill-seekers who wager on the life and death of others.

• Siena Blaze
• Fabian Cortez
• Graydon Creed
• Fenris
• Trevor Fitzroy
• Selene Gallio
• Gamesmaster
• Shinobi Shaw

• Major Domo
• Mojo
• Warwolves

Depowered mutant terrorists on the hunt to regain their powers.

These villains normally operate alone, attacking the X-Men, rather than teaming up with a group of allies.

• Cassandra Nova
• Krakoa
• Mojo
• Omega Red
• Onslaught
• Dark Phoenix
• Proteus
• Senator Robert Kelly
• Vulcan
• Adversary
• Ahab
• Ani-Mator
• Arcade
• Azazel
• Belasco
• Lucas Bishop
• Cyber
• Danger
• Deathbird
• D'Spayre
• Erik the Red
• Garokk
• Gauntlet
• Kulan Gath
• Henry Peter Gyrich
• Iron Patriot
• Khan
• Kuragari
• Living Monolith
• Masque
• Maximus Lobo
• Mesmero
• Mortis
• Moses Magnum
• David Moreau
• Nanny
• N'astirh
• D'Ken Neramani
• Ord
• Orphan Maker
• Pandemic
• Predator X
• Romulus
• Shadow King
• Silver Samurai
• Sugar Man
• S'ym
• Vargas
• Viper
• Wendigo
• X-Cutioner
• Deadpool

• List of X-Men characters
• List of X-Men teams