He got his start at DC Comics in 1968 and eventually moved onto Marvel Comics in 1974, where he became one of its editors. While at Marvel, he worked on The Tomb of Dracula (where he co-created the character of Blade), The Amazing Spider-Man, and The Fantastic Four, among other titles. He returned to DC in 1980 and worked on their Teen Titans comic, relaunching it as The New Teen Titans. During his time at DC, he was one of the main editors of the Star Trek line of comic books.