Ray Bradbury, it seems, has met almost everyone. Katherine Hepburn? Yes. George W. Bush? Yes. Aldous Huxley? Yes.
Bertrand Russell? Actually, yes.
Superman? Well, apparently, yes!
At least, according to David Surridge, posting on Black Gate: Adventures in Fantasy Literature. Surridge reviews the movie tie-ins and other writing of Elliot S. Maggin, author of Miracle Monday (1981), in which Ray Bradbury appears - fleetingly - as a fictional character, along with his late wife Maggie and a certain Walt Disney.
I thought Harlan Ellison's recent screen appearance alongside Scooby Doo was amazing, but it seems Bradbury got there first, appearing alongside a fictional character nearly thirty years ago!