- He is a major mainstream comic book talent who started with Charlton Comics, most notably with "Doomsday +1"
- His most notable work includes his run on Marvel Comics' "Uncanny X-Men" with writer Chris Claremont which contains some of the most famous X-Men stories such as "The Phoenix Saga" and "The Days of Futurepast." as well being responsible for popularizing characters like Canadian characters like Wolverine and the superhero team, Alpha Flight.
- He also had an run on Movel Comics' flagship title, "The Fantastic Four", which is second only to series creators Stan Lee and Jack Kirby's tenure on the title in popularity and acclaim.
- He also was responsible for the major overhaul of DC Comics' Superman in 1986 in order to revitalize the character which included making him less powerful with his Earthly parents still alive while making Lex Luthor a powerful and corrupt mega-coporate head.
- He has also worked with a wide variety of other DC and Marvel characters which include The Incredible Hulk, Captain America, OMAC: The One Man Army Corps., Wonder Woman, Spider-Man in individual runs in the characters' respective titles, and Mini Series such as Legends.
- Also created the Next Men for Dark Horse Comics.
- (1998) He acted in Alan Bennett's play, "Kafka's Dick," in a Peter Hall Company production at the Piccadilly Theatre in London, England with John Gordon Sinclair, Jason Watkins, Julia McKenzie, Eric Sykes, and Denis Lill in the cast.