The Second Doctor has been partially regenerated by the Time Lords as punishment for breaking the non-interference policy, but the process is stopped halfway, leaving the Doctor an amalgam of his second and as-of-yet future incarnation...
as Second-and-a-Half Doctor
as Second Doctor (archive footage)
as Third Doctor
as Voix
as Scribe
as Auriga
as Callisto
as Adreinna
as The Covellitor