Boothaler: marauder, plunderer

Burglar: one who breaks into, and steals things from, other people's houses. (If you break into and steal stuff from your own house, you're just a nut.)

Diver: fig. a pickpocket

Fence: one who trades in stolen goods

Footpad: one who robs pedestrians

Outlaw: a man wanted by the law

Pickpocket: one who picks pockets

Poacher: one who illegally kills animals, usually on somebody else's land

Silk-snatcher: one who steals bonnets

Stewsman: probably a brothel keeper - "since the words stew and stewholder both mean a bawd, I'm guessing that a stewsman would be a brothel-keeper as well. Whether bawdry counts as a criminal activity varies at different times and places."

Thimblerigger: a professional sharper who runs a thimblerig (a game in which a pea is ostensibly hidden under a thimble and players guess which thimble it is under)

(Found on http://www.svincent.com/MagicJar/Economics/MedievalOccupations.html)