His first major work was the book Doomsday +1 for Charlton Comics, then he went over to Marvel doing different series, most notably Iron Fist and Marvel Team-Up. His career caught fire when he teamed up with Chris Claremont on Uncanny X-Men and began their series-defining run on the title.
As we all know, Byrne left Marvel for DC and the lightning struck for a third time as Byrne took on the Dc's flagship character, Superman.
In the Man of Steel mini series, Byrne once again pared the character down to all the concepts that made Superman who he was and redefined him for modern readers. Before Brian Michael Bendis, who's known for churning out 3 or 4 titles a month, John Byrne handled the writing and art on Superman and Action Comics as well as writing the other 2 core books.