Valeyard

The Valeyard is a Time Lord who, according to the Ainley Master is an amalgamation of the Doctor's darker sides from between his twelfth and final incarnation, who serves as the secondary antagonist of Season 16, despite only appearing in the last 2 episodes of the season. The Sixth Doctor takes a few opportunities to give him variations of his name, such as "Boatyard", "Scrapyard" or "Rail yard".

Personality
The Valeyard is cunning and verbal, similar to several of the Doctors. He is prone to outbursts, but he is normally calm and collected. However, his actions are constantly defined by his egotism. He is willing to sacrifice anything and everything to ensure his own existence, even breaking the laws of time and kill his own past self in an attempt to prevent Sutekh from being defeated.