David Tennant was 16 in Biting the Hands when he played the character '3rd Squaddie'.
That was over 35 years ago in 1989.
This was his first recorded movie acting credit (although may not technically be his first actual acting role).
Today he is 53, and has starred in 102 movies in total, 99 of those since Biting the Hands was released.
In Biting the Hands, I think David Tennant looks: