Kihaku Hanta

Kihaku is a bounty hunter aswell as a hitman of sorts. He currently serves Jean-Claude and has for -- years as a Dredge though both parties have stated that Kihaku is strong enough to break Jean-Claude's hold.

Devils Fruit
Doutai Doutai No Mi (Masterreaper)

History
Kihaku started out as a hitman but decided that "Normal" humans were too easy to kill. He then turned his sights to Devils fruit users, he has never turned down a job if offered an amount he thought reasonable for the target though he has stated that he refused to take one any of the admirals.

Training
Kihaku claims to have been trained by the Marines, World Government, Cipher Pol (though he never stated which branch), and the revolutionaries.