Mark Millar is a writer ("Superman, Red Son", and a brief run on "Adventures of Superman"), currently writing for Marvel with Jeph Loeb.
He does say of Christopher Reeve
Christopher Reeve wasn't an actor to me. These were the Adventures of Superman being beamed from a parallel earth and available on the glorious big screen. In the brief period where I've written Superman, I've only ever heard Reeve's voice. His face is an synonymous with the character to me as a Curt Swan face. He was the living, breathing Superman, and, for people like me in their 30's, can never be surpassed.
