Tim Plester is an English actor. He has appeared in several TV series such as Silent Witness, Casualty, Life On Mars, Doctors, Waterloo Road, The Bill and Doctor Who. He has also appeared in feature films like It's All Gone Pete Tong (alongside Paul Kaye), Kick-Ass and Lockout. In Game of Thrones, he is playing Walder Rivers. He joined the cast as a guest star in the third season, and returned to reprise his role in the sixth season. He is also a playwright. He wrote an award winning short film called Ant Muzak (2002), which starred fellow third season cast member MacKenzie Crook.