Roy William Thomas (born in Missouri on 22nd November 1940) is an American comics writer and editor who succeeded Stan Lee as Editor-in-Chief of Marvel Comics, and later worked for rival publishers DC Comics. He is notable for having introduced Conan to comics, and for his large body of work on 'Golden Age' characters such as the Justice Society of America.
During a long and varied career, Thomas worked on numerous series including Fantastic Four, X-Men, Avengers, Invaders, Iron Fist, Nick Fury, Spider-Man, Nightmask, Captain America, Dr. Strange, Thor, Hulk, Defenders, Tarzan, Batman, Arak Son of Thunder, All-Star Squadron, Infinity Inc. and Wonder Woman. He is also a noted comics historian, and the creator of Red Sonja, who was loosely based on a rather different character created by Robert E. Howard.
From the point of view of British comics, though, he's basically here because he created the Black Knight, a minor member of the Avengers who later became a much more significant character at Marvel UK, and co-created Spitfire and Union Jack for The Invaders.