The Weasel, real name Howard Montague, was an aggresive object collector and owner of the Pen. He was responsible for the disapperance of Anna Miller, and he tricked her father Joe Miller into stealing the Clock from Karl Kreutzfeld. Howard then tried to kill Joe with the Pen but failed as he was inside the room, prompting Joe to steal the pen and throw Howard back into Kreutzfeld's vault. Howard did not appear in the show until after Kreutzfeld's betrayal, where he assissted Joe by lending him his car.
He is thought to be less knowledgable of objects, since he thought Joe Miller's gun was an object. He was also a believer in the theory of the Prime Object, and incorrectly thought it to be the Clock (Although this may have been all part of his attempt to trick Joe). He was not a member of a Cabal, nor was he a proper object collector. Instead, he simply used his pen to swindle people and steal either money or valuable objects. He owned the key for a short time, but whether or not he actually got to use it is unknown.