Haunted: aka, Jack. A student ghost at Hogwarts. Killed by Voldemort, and has been there ever since.
????????: An unnamed ghost who mostly lives in the Muggle world, causing trouble. His favorite hobbies are: Crashing parties, interrupting special events, and being a complete pain.
Cal Markman: A Werewolf, who, always winds up working for the wrong people. Never get in his way, though, Werewolves are strong.
The Boss: A sinister villain who is very mysterious. No one has a clue about his name. Weak himself, the man can summon an entire army of lackeys.
Mr. J: A bartender in Diagon alley. Knows many Hogwarts secrets, just refuses to share.
Guard no. 34: A lackey for The Boss. His name is unknown to most, even though he is a main component to The Boss's plans.
Henry Johnson: I don't think "detective" is the right word for this guy. He calls himself one, but hardly gets work done. He mostly just spends his days in the Grand Jewel Casino.