Brian - Half Human, half Siren.
Tim - Werewolf.
Toby - Half Human, half Vampire.
Jeff - Vampire.
Liu - Human.
Nina - Half Vampire, half Human she purposely got herself turned in hopes Jeff would find her more attractive.
Jane - Human.
Clockwork - Half Demon, half human.
Sally - Human now ghost.
BEN - Half Siren, half Demon.
Slenderman (The Slender brothers) - Demons.

Other, maybe later, Characters.

Tiffany - Human.
Fred - Werewolf.
Addy - Siren.