An incarnation of the Doctor was seen during his mindbending contest with Morbius. (TV: The Brain of Morbius, AUDIO: Cold Fusion) According to one account this man was the Other, whom the First Doctor was a reincarnation of. (PROSE: Lungbarrow)
behind the scenes
The face of this Doctor were first introduced in TV: The Brain of Morbius but it was not until AUDIO: Cold Fusion thirty years later, in 2016 that they were confirmed to be incarnations of the Doctor.