Excalibur is a Marvel Comics superhero group, an off-shoot of the X-Men, usually based in the United Kingdom. Conceived by writer Chris Claremont and artist/co-writer Alan Davis, the original Excalibur first appeared in Excalibur Special Edition (1987), also known as Excalibur: The Sword is Drawn.
The first Excalibur consisted of the British superhero Captain Britain, his lover Meggan, and several one-time members of the X-Men and related mutant teams. An eponymous series featuring the team lasted from 1988 until 1998. Originally, the series involved cross-dimensional travel that incorporated as many elements of Captain Britain’s mythos as it did the X-Men’s.
Captain Britain reformed Excalibur to defend London in a series entitled New Excalibur, which ran from 2005 until it was replaced in 2008 by Captain Britain and MI13.
Between Excalibur’s disbandment and reformation, a short-lived series entitled Excalibur chronicled the efforts of X-Men founder Professor Charles Xavier and his former nemesis, Magneto, to rebuild the mutant homeland of Genosha. Although written by Claremont with the same title, it had no connection to the superhero team.