Anyone from the necromancy books from Garth Nix, to be honest. The Sandman Chronicles' Death, (and Dream), enough for Susan to start a Not that Morbid Club.

Personally I'd love more (?) from the Parasol Protectorate, Luna Lovegood, the Narnia Queens, Ororo, Jenny Bonnet from Frog Music, Any Saga character and basically everyone else I'd love to play with. Alyss Heart as well, if I won't app her one day.