Tracy Jordan is a fictional character on 30 Rock, played by Tracy Morgan.
The character is a successful African-American movie star with a reputation for unpredictable, highly erratic behavior.
This reputation is well-earned and much of it is an intentional attempt on his part to maintain his "crazy" persona in the eyes of the media.
In the pilot, Jack Donaghy forces Liz Lemon to hire Tracy Jordan as the new star of her sketch comedy program The Girlie Show.
To the chagrin of Liz, Jack renames the show TGS with Tracy Jordan in the following episode. Tracy has remained star of TGS ever since.