Omega Sentinel is a superhero later supervillain appearing in American comic books published by Marvel Comics. The character is associated with the X-Men and its spinoff Excalibur.

Excalibur is a superhero group appearing in American comic books published by Marvel Comics. They are depicted as an offshoot of the X-Men, usually based in the United Kingdom. Conceived by writer Chris Claremont and artist/co-writer Alan Davis, they first appeared in Excalibur Special Edition #1 (1987), also known as Excalibur: The Sword is Drawn. Stories involving this team have featured elements of both the X-Men and Captain Britain franchises, frequently involving cross-dimensional travel.