Theta Sigma (Regenerators' timeline)
From Tardis Wiki, the free Doctor Who reference
Commentator Theta Sigma was a version of the Doctor who existed in an alternative timeline where Rassilon failed to finish the Eye of Harmony before his death. Consequently, Theta Sigma never left Gallifrey. He became a commentator rather than a renegade Time Lord. He appeared to be in his sixth incarnation. (AUDIO: Forever)
In the proper timeline, "Theta Sigma" was the Doctor's nickname at the Academy. (TV: The Armageddon Factor, TV: The Happiness Patrol)
