Ninth Doctor (The Curse of Fatal Death)

The Ninth Doctor was a possible future incarnation of the Eighth Doctor.

Biography
When the eighth incarnation of the Doctor looked into the Tomorrow Windows, he saw this incarnation as a possible ninth incarnation, as well as another which would not be and the one which would. (EDA: The Tomorrow Windows)

This incarnation met the Master on the planet Tersurus, after the Master asked him to, and announced his retirement from universe saving. He wished to settle down in domestic bliss with his companion Emma. He confronted the Master's various traps before being captured by the Daleks. The Doctor warned the Master using smells, the language of Terseran, about the creatures' plans to exterminate him once his usefulness was at an end.

The Doctor was hit by a Dalek energy beam and regenerated into his next incarnation. (DW: The Curse of Fatal Death)

Behind the scenes

 * Like The Curse of Fatal Death, this incarnation of the Doctor was not considered canon. However, EDA: The Tomorrow Windows later brought him into canon as a possible future incarnation.