Robert O'Reilly (born March 25, 1950, in New York City) is an American film, stage, and television actor and director. He is best known for his role as Chancellor Gowron, the leader of the Klingon Empire, in the Star Trek franchise—particularly on Star Trek: The Next Generation and Star Trek: Deep Space Nine.

O'Reilly’s career spans over 100 films and TV episodes, often portraying antagonistic or villainous characters. He appeared in series like Cheers, Knight Rider, MacGyver, NYPD Blue, and films such as The Mask. He has also performed on Broadway and at Carnegie Hall. Notably, he received a Drama-Logue Award in 1981 for directing the play Getting Out.