Famous for his portrayal of Richie Green in the 1980s musical martial arts movie The Last Dragon, O'Brien is also known for his role as Allan in the 1985 film Rappin'.
When he was just thirteen years old, he appeared in an episode of CBS Children's Mystery Theatre.
He played a small role in the crime movie New Jack City.
A native of New York, New York, he died in his home city in his early forties. His older brother, Guy O'Brien, belonged to a hip-hop group called The Sugarhill Gang.
He and the singer known as Vanity were both in the cast of the 1985 film The Last Dragon.