A charlatan or quack.
"Well said again!" cried good Mr. Wilson. "I feared the woman had no better thought than to make a mountebank of her child!"
"Oh, not so! - not so!" continued Mr. Dimmesdale. "She recognizes, believe me, the solemn miracle which God hath wrought in the existence of that child . . ."
From Hawthorne's The Scarlet Letter.