Thomas A. Harris

Harris was a psychiatrist who had run psychiatry for the US Navy and taught at the University of Arkansas when he published I'm OK, You're OK in 1967, popularising Eric Berne's transactional analysis: the idea that people speak from a parent, adult or child position, and that most conflict is a mismatch between those. It sold over fifteen million copies. Transactional analysis has largely dropped out of clinical use and never had strong trial support, though the vocabulary survives. He died in 1995.