If Tennessee Williams' works are largely autobiographical, which character in A Streetcar Named Desire is considered closest to Williams himself?
In A Streetcar Named Desire, Tennessee Williams is identified in two characters: Blanche Dubois and her husband, Allan Grey.
In Blanche we see the debauched Williams, addicted to pills and alcohol, slowly descending into depression and self-destruction, and trying her best to come back to the surface to no avail.
In Allan Grey, we see Williams also in that they are both homosexual and seem to have a problem with leading double lives and accepting their identities until their deaths.
The link includes more information on Tennessee's biographical facts to help you see more similarities.
Just so you don't go away with errant information, Williams did not commit suicide. He choked on a bottle cap. Theories differ on how it happened, but suicide is not one of the possibilities usually considered.