The casting change will take place following Season 2 as the series was designed to feature the royal characters as they age. Olivia Colman will be taking over the role of Queen Elizabeth II from Claire Foy and Helena Bonham Carter is set to play Princess Margaret in place of Vanessa Kirby.
Menzies will be joining the cast when production begins in the summer in the U.K., Deadline reported. The actor is known for portraying Brutus in HBO's Rome, as Edmure Tully in Game of Thrones and as Frank Randall and Black Jack Randall in Outlander. He will be seen as the Duke of Cornwall in BBC and Amazon's King Lear and also stars in AMC's The Terror.
"Say hello to your new Prince Philip in @TheCrownNetflix Season 3: Tobias Menzies!" Netflix said on Twitter.
Paul Bettany was originally in talks to portray Prince Philip before he dropped out of the project.