Cyborgs

A cyborg is a human or other life form who has been modified with machinery and metal for better functioning. These mechanical enhancements can include cybernetic replacements for missing organs or body parts, metal skin for extra protection, and weapons installed somewhere in the body.

Cyborgs in One Piece
In One Piece, cyborgs are somewhat rare, as the technology required for their creation is somewhat advanced. Those who are cyborgs have an advantage in battle, as they are more powerful than regular humans in both offense and defense.

Though they have mechincal parts so long as their brain is not altered in any way they maintain their free will. As was revealed was the fate of Bartholomew Kuma loosing their free will leaves them "dead" and reduces them to being nothing more then a tool. It is also claimed by Doflamingo that they have no memories or recollections of their past life, Kuma had become obedient to the words of the World Government he hated so much. In an earlier instance, when Nami hears a heartless remark from Franky she asks him if he replaced his heart, to which he apologises in metaphoric terms that he "never meant to go that far", confirming Franky unlike Kuma has never lost his humanitity.

List of Cyborgs

 * Franky
 * Bartholomew Kuma
 * Pacifista
 * Taroimo
 * Several Inhabitants of Karakuri Island