A former pirate with a bounty of 296 million beri, Bartholomew Kuma is one of the Shichibukai—and by most accounts, the most obedient one the World Government has. He's known for being calm and composed, doing what needs to be done without fanfare. Like Mihawk and Doflamingo, he showed up at the Mariejoa summit after Crocodile's defeat in Alabasta.
Kuma is massive—well over twenty feet tall, comparable in size only to Moria's true form. He's got what appears to be teleportation abilities, popping in and out of sight instantly. More notably, he can make people vanish just by touching them, sending them to wherever they wish to be (as happened with Perona). The full mechanics of his powers aren't entirely clear, but his habit of asking people where they'd like to be "transported" to suggests he's got some control over it.
There's a stark contrast between his violent past as a pirate—Perona's spoken to his brutal reputation—and his current, almost gentlemanly demeanor. These days, he's reserved and methodical, often carrying around a large bible. It's pretty obvious he's modeled after Bartholomew "Black Bart" Roberts, the gentleman pirate known for his religious conviction.
Kuma's been involved in high-level World Government business, including discussions with Moria about Marshall D. Teach joining the Shichibukai and coordinating efforts against the Straw Hats. He also knows about Portgas D. Ace, though he hasn't personally encountered the Straw Hat crew.
Content compiled by AnimeList.moe from publicly available sources.