He played several characters in Star Trek: The Next Generation, starting in the first season, including the first Romulan on the series, Commander Tebok, and the first Cardassian, Gul Macet, in the 1991 episode, "The Wounded," of that series. He also played a poker player who speaks French to Data in the episode "Time's Arrow". In 1993, Alaimo began playing Gul Dukat in Star Trek: Deep Space Nine. Gul Dukat was a recurring character, who appeared in 37 episodes of that series, and is his best-known character. He also appeared in a season two episode of 21 Jump Street.