When did David Tenant change his name?

Answer 1

There was already an actor called David McDonald registered with the actors union, so David Tennant had to register differently. He chose to use a different surname.He got his new last name from Neil Tennant when he looked in a magazine

Answer 2

His real name is David John McDonald, but two actors cannot share the same name and there was already an actor called David John McDonald so he changed it, he found his name by searching through a magazine.

Answer 3

He first took on the name Tennant when he was 16 and applied to join the acting union Equity, after his first TV job.