Seconded. Also while it's fun to show off your bad guys, anytime you put on NPC "on camera" it means they are fair game and the PC's can kill them. So if this is the campaign bad guy and he's not strong enough to take the whole party in a straight up physical fight keep him hidden.
A trick I like doing is hiding the bad guy in plain sight. If the players have a place they hang out alot, have the bad guy be an NPC that they interact with alot on a friendly level. If Garm is a one armed gent, make it him an older guy, who gives them fatherly advice. A mentor. OR have them save him from some other group. Make a connection with him so they might be less willing to kill him when they finally find out he's the BBEG.
Also, use compels combined with the locations and face's you've created to throw Monster of the Week type challenges to keep the group from pursuing the gang at every turn.
As to balancing them mechanically, well we'd need to see your PC's stats. Some LT idea's though. A recent red court vamp in hiding because he angered a really powerful noble. If he pops his head out at all he's liable to lose it so he needs to stay on the DL. A dispasionate alchemist (focused practioner) making drugs for the gang so he can study the effects. A bad boy thug, either lycan or pure mortal. Was the star athlete in high school, couldn't play pro for whatever reason. He is the muscle enforcer. A retired or active cop, who's on the payroll, because his daughter is a werewolf, Red court infected, wizard, changeling, ect and they know and are either helping him conceal it and deal with it, or are simply blackmailing him. Maybe a bit of both. The pyromancer/maniac fire immune explosives expert. Sometimes his bomb's go off early, but he doesn't care, long as something exploded.