Stephen Noonan

 voiced the First Doctor in several of The First Doctor Adventures audio stories. He also voiced several other characters for Big Finish Productions.

The First Doctor Adventures
As the First Doctor
 * The Outlaws
 * The Outlaws
 * The Miniaturist

Other Roles

The Third Doctor Adventures

 * Kaleidoscope - Solokov / Keith Hazel / Fairford / Phantom Pilot / Nanobots