The man who owns the nightclub Harlem's Paradise and everything that runs through it, and who does not make it to the end of his own season.
Cornell “Cottonmouth” Stokes owns the Harlem’s Paradise nightclub and deals in illegal operations behind it. He is the cousin of Mariah Dillard, the councilwoman, and Mahershala Ali plays him in the first season of Luke Cage, with Elijah Boothe as the young Cornell. Ali described him as a Godfather-type villain; Jeph Loeb, then the head of Marvel Television, called him the other hero of the story.
Ali took the part knowing that the character would die early. Wikipedia quotes him comparing it to shooting a film rather than entering another marriage of unknown length, and saying it was the first time he had found himself excited by a character’s departure.
Minor spoiler
Mariah does, in a rage. She first frames Luke Cage for it, and later shifts the blame to Diamondback. The cast table on Wikipedia’s list has him in the second season only in archive footage, so that season is not in his list.