Third Doctor

In a parallel universe, the Third Doctor was an iteration of the Doctor.

Biography
The Third Doctor played a part with an event involving the Uxariean Doomsday Weapon. (TV: Colony in Space, AUDIO: He Jests at Scars...)

After the Valeyard stole the Doomsday Weapon and used it on Gallifrey, he undertook various corrections of history. He told Mel that he unintentionally destroyed possibilities in which he existed. (AUDIO: He Jests at Scars...)