20. Book
Appeared in: Firefly, Serenity Here's another one of those sort-of cliches that just needs to be in any modern western, and especially in a space western: the preacher with the mysterious past. In Firefly, that was Shepard Book, and he wound up becoming a rather popular character on the show. No official explanation for his past is ever made during the show's run, but at one point, while injured, his identity card ensures he gets lifesaving treatment from Alliance (think Empire) doctors. That aura of mystery serves Book well, and while a comic run would later explain his background, it was generally more fun not knowing. It's what made his character great: trying to puzzle out how the simple preacher could be connected to something so clearly big in his past.