Well, Joaquin Phoenix was Superboy, at least in one of the most marvelous dream sequences I've ever seen.
Here's the story: once upon a time, a 15-year-old Phoenix appeared in a 1989 episode of "Superboy" called "Little Hercules." But don't mistake little Billy for the Greek demigod of lore, though you would be forgiven for such a mistake given Phoenix's flowing locks of Kevin