Jet Black is a character in the excellent anime serial Cowboy Bebop.
Jet Black: The Character
Jet appears first in Session 1, and was originally voiced by seiyuu Unshou Ishizuka (石塚運昇, who also performed the voices of Professor Oak in all the Pokemon movies/serials as well as Guld Bowman in Macross Plus). In the English dub he's voiced by actor John "Beau" Billingsly (who is also the familiar narrator for the English dub of Outlaw Star, and minor part in Gundam 0083).
Jet Black: A Complex Man
Jet Black (also known as Black Dog) is Spike Spiegel's bounty hunting partner. This bald-headed, blue-eyed, 6'2" hulk was born December 3, 2035.
Jet owns the Bebop, a large, seaworthy space vessel, that he bought second hand on Ganymede. (Ganymede had salt water oceans and a thin oxygen atmosphere even before terraforming.) He's a sensible, level-headed man and like others aboard the Bebop he carries a sad past: His partner betrayed him and the woman he loves left him eight years prior. For being 36 though, he's wise beyond his years, and pretty "square" with his bonsai trees, and strong work ethic (he's usually scouted out the next bounty before Spike). He's the father figure to the younger two and as a result Jet is the head chef on the Bebop since neither Spike nor Faye can be bothered with cooking. The sessions involving the past with his ex-partner Fad, and his ex-girlfriend Alisa, and later his time with Meifa show the depth of his character.
How Jet Lost His Arm
Before Jet was living hand to mouth on a second hand fishing ship, scrapping for bounties he was an agent for the ISSP, an FBI-like organization, basically a space cop. In this line of work he picked up the nickname 'Black Dog' because "once he got his teeth into something, he never let go."
However, despite Jet's tenacity, the solar system was generally going to hell. His partner at the time, Fad, realized that organized crime syndicates were rapidly becoming the real enforcing body in the solar system, and the police could do very little to control them; Fad joined the syndicates as an inside man. Since Jet Black would never sell-out the syndicates had to get him out of the way, and tasked his partner with killing him. Jet was shot by a figure in shadow but luckily he only took it in the arm and as a result, Jet had to have it replaced with a cybernetic version. He never knew that it was his partner until a decade later, when the two met up again. Fad, tries to finish the job, but due to his feelings of guilt allows Jet to shoot and kill him.