Aidan Cook

 appeared in three Doctor Who series 7 episodes, portraying the Mummy in the The Rings of Akhaten, the Crooked Man in Hide, and a Cyberman in Nightmare in Silver. He subsequently appeared in the 50th anniversary story The Day of the Doctor and the 2013 Christmas special The Time of the Doctor as both a Zygon and a Cyberman respectively. He later starred in The Zygon Invasion and The Zygon Inversion as a Zygon.

Cook previously wore prosthetic make-up when appearing as the Two-Headed Shop Owner in the fantasy comic book movie, Hellboy II: The Golden Army.