A swindler; a charlatan; a trickster.
1) The mountebank came into town trying to convince people to buy his "magic shampoo" for an inordinate sum.
2) The "friendly banker" was revealed to be a mountebank trying to steal the town's wealth.
Apollo Robbins, The Master Pickpocket: Tricks of the Trade
This would fall under the definitions of "trickster".