Guy Domville Siner was born in New York City on October 16, 1947, the son of an English mother from Bexhill-on-Sea and an American father from Manhattan.

After attending St Edmund's School in Hindhead, he moved to London to receive training as an actor at the Webber Douglas Academy of Dramatic Art.

Siner's TV credits include Z Cars, Softly, Softly: Taskforce, Doctor Who (Genesis of the Daleks), I, Claudius, Secret Army, You Rang, M'Lord?, 'Allo 'Allo!, The Brittas Empire, Seinfeld, Knots Landing: Back to the Cul-de-Sac, Babylon 5, Martial Law, Diagnosis: Murder, That's My Bush!, Star Trek: Enterprise, ChuckleVision, Family Tree and The Crown.

In 1980, Siner portrayed director Mack Sennett in The Biograph Girl, a short-lived West End musical about the silent film era.

[3] Siner voiced several Star Wars video games: He worked as a script editor on two expanded universe Doctor Who stories in 2008.