The Collecter's real name is Mark ... .He used to work for the Authority, but broke up after the Babalon-Summond failed, that he tried to do with his friends Henry Walker and Charles Taylor, John's father. He is a man who loves to steal and stash rare items of the Nightside. Walker killed him to obtain a portable timeslip and an item that may transfer the mind of one person into another's body. The Collecter also had his own security force of cat-like robots. His base with his collection often change places, one of this places was the Sea of calm at the moon.
He can slip though space and time with a portable timeslip (even though it was mentioned he posseses a ability to do it). Further more the Collecter holds an unique collection of rare, powerful and dangerous artefacts such as the Speaking Gun or the Unholy Grail. Pobably he never ever will use one.