Mark Williamson, 1993 Upper Deck #722

This is the first card I can remember seeing that tears down the fourth wall. For some reason, the Upper Deck photographer perched over the shoulder of another photographer and captured the process of Mark Williamson posing for that other shutterbug. Very meta, huh? I'll say this for Upper Deck; they were never afraid to try something new. We're talking about a baseball card featuring a middle reliever. You might as well break the mold a bit.