Adventures in Time and SpaceEdit
The Sixth Doctor's regeneration was initially unstable, and he nearly strangled Peri before he came to his senses. He encountered many old foes including the Master, Daleks, Cybermen and Sontarans, and even shared an adventure with his own second incarnation. Later, the Doctor was put on trial for the second time by his own race, the Time Lords. The prosecutor at that trial, the Valeyard, turned out to be a possible future, and evil, incarnation of the Doctor himself. The events of the trial tangled the Doctor's timeline slightly, as he left in the company of Mel, whom he technically had not yet met.
When the TARDIS was attacked by his old enemy the Rani, the Sixth Doctor was somehow injured and regenerated into the The 13th doctor; the exact cause of the regeneration, however, has never been revealed on-screen.and now he is played by Nik Kershaw to re-do Time and the Rani and now a daughter called Izzy