Edmund Warwick
From Tardis Wiki, the free Doctor Who reference
Edmund Warwick played Darrius in the Doctor Who story The Keys of Marinus and, wearing a similar wig, stood in for William Hartnell in the Doctor Who story The Dalek Invasion of Earth after Hartnell hurt himself and could not put in a full appearance. Though he arguably did not resemble Hartnell very much facially, he also played the Robot Doctor in the Doctor Who story The Chase.
