William Joseph Martin (born May 25, 1967), formerly known as Poppy Z. Brite, is an American author. He initially achieved fame in the gothic horror genre of literature in the early 1990s by publishing a string of successful novels and short story collections. He is best known for his novels Lost Souls (1992), Drawing Blood (1993), and Exquisite Corpse (1996). His later work moved into the genre of dark comedy, with many stories set in the New Orleans restaurant world. Martin's novels are typically standalone books but may feature recurring characters from previous novels and short stories. Much of his work features openly bisexual and gay characters.

Born as Melissa Ann Brite, now going by Billy Martin, he has written and talked much about his gender dysphoria/gender identity issues. He self-identifies almost completely as a homosexual male rather than female, and as of 2011 has started taking testosterone injections. His male name is Billy Martin. He lived in Chapel Hill, North Carolina and Athens, Georgia prior to returning to New Orleans in 1993. He loves UNC basketball and is a sometime season ticket holder for the NBA, but he saves his greatest affection for his hometown football team, the New Orleans Saints.