I don't think characters need to be deep to be memorable. The most memorable character from the Baldur's Gate series, and the only one notable enough to get his own Wikipedia article[0], is Minsc. Minsc is the cliched stupid-but-brave warrior hero we've seen hundreds of times before, but he has one memorable gimmick: his pet hamster Boo. The inherent comedy of this combination is enough to make him very popular. "Go for the eyes, Boo. GO FOR THE EYES! RrraaaAAGHGHH!"