Christopher Eccleston and Sylvester McCoy are the only doctors not to have regenerated on screen using the actor from his previous incarnation. Colin Baker refused to appear in the sequence involving him regenerating into Sylvester McCoy, so McCoy performed both parts of the sequence wearing a wig to resemble Baker
The Tenth Doctor was the tenth incarnation of the renegade Time Lord known as the Doctor. Unlike his immediate predecessor, who was plagued by melancholy due to his actions during the Last Great Time War, this incarnation was much more outgoing and genial, a demeanour that hid the "survivor's guilt" that had plagued him since the war. Over his life, however, the weight became much more pronounced. He was haunted by companions lost, enemies believed long-dead and events that threatened the fabric of time itself. He met his end after he absorbed a huge quantity of nuclear radiation whilst saving the life of his friend, Wilfred Mott, leading to his regeneration into his next incarnation.