A superhero team published by Marvel Comics. Excalibur first appeared in Excalibur #1 in 1988.

After the Mutant Massacre in which the forces of the villain Mister Sinister decimated the ranks of the super-hero team the X-Men, two of their members Nightcrawler and Shadowcat were sent to Muir Island, the base of a mutant research station headed by Dr. Moira MacTaggert. While the two were recovering, it was believed that their fellow teammates had given up their lives to protect the world from the evil influence of the Adversary.

About the same time, Rachel Summers, the daughter of Scott Summers (the mutant X-Man Cyclops) and Jean Grey (Marvel Girl/Phoenix) from an alternate timeline, escaped from the clutches of the extra-dimensional menace Mojo. Arriving in England, Summers, who had inherited a portion of the Phoenix force was pursued by agents of Mojo in the form of Warwolves. Phoenix was aided by Nightcrawler and Shadowcat as well as the British heroes Captain Britain and Meggan. After defeating the Warwolves, the five heroes decided to continue to work together, calling themselves Excalibur after the legendary sword of King Arthur.

The team had many adventures, at one point hopping dimensions due to the actions of a sentient mechanical device called Widget. They fought such groups as the Technet and Crazy Gang and later became embroiled in opposing the forces of an black-ops group called Black Air.

The group later expanded to include the Phalanx/human hybrid called Douglock, the former X-Man Colossus and a former British secret agent named Peter Wisdom. The group disbanded after Captain Britain and Meggan were married and the three former X-Men decided to return to the United States.