Villains that screw you over by fulfilling your request.

Jack Horner- Puss in Boots: The Last Wish

Horner offered two thieves their weight in gold to retrieve the map to the wishing star. When one of them annoys him, Jack confirmed they were twins before turning one into a gold statue. The remaining twin now has her literal weight in gold.


Captain Hector Barbossa- Pirates of the Caribbean Curse of the Black Pearl 

Did this twice. Seriously, be hyper specific when bargaining with the man. 
During his parley with Elizabeth, Barbossa kept his word to leave Port Royal as soon as he got the medallion. But when she protested that she had to be returned to shore, Barbossa counters that he must do nothing since she never included that in their negotiation. Also, he's a pirate and she's not, fuck you.

Then again with Will Turner, he has Barbossa dead to rights and can ask for anything. What does he ask for? Free Elizabeth and don't harm Jack Sparrow's crew. Once Liz is walking the plank, Will calls foul, and Hector took exception to that, "I swore she'd go free, but twas you who failed to specify when or where".

Rumpelstiltskin - Shrek Forever After 

Offers Shrek a chance to live like a real ogre for a day in return for a day from Shrek's life. Shrek was screwed the moment he agreed. This wish allowed Rumpelstiltskin to usurp the Kingdom since the day he took was the day Shrek was born, eliminating the chain of events that allowed Shrek to save Fiona.

(Loved Trope) Villains with Malicious Compliance