Rassilon (The End of Time)

Late into the Last Great Time War, an incarnation of Rassilon whom one account nicknamed the "Crewcut" Rassilon, led the Time Lords' final stand against the Daleks and the other horrors birthed during the War, such as the Could've Been King and his Army of Meanwhiles and Neverweres. Rassilon planned to initiate the Final Sanction with his High Council, breaking the time lock and unraveling the Time Vortex itself in order to destroy creation and leave the physical universe. However, his plot would ultimately be foiled in the eleventh hour by the Tenth Doctor and, with the help of a traitor on his own Council.

Pre-Time War origins
By some accounts, this incarnation originated from and was active in ancient Time Lord history, (PROSE: Snow White and the Seven Keys to Doomsday) being involved in the Alliance of Races and fighting in the Great Inferno (COMIC: Terrorformer, Gangland, The Hyperion Empire) as well as the creation of TARDISes. (COMIC: The Lost Dimension)

Origins during the Time War
By one account, this incarnation was the immediate successor to the incarnation of Rassilon who slept in the Tomb of Rassilon. (PROSE: Engines of War)

Other accounts indicated Rassilon had at least two other incarnations since his resurrection. (AUDIO: Homecoming)

Wartime actions
Rassilon retro-evolved dozens of Time Lords to become a possibility engine to aid him in victories throughout the Time War, creating the discarded race of the Interstitials and succeeding with Borusa. (PROSE: Engines of War) When the Time Lords feared that the Compassionate would side with the Daleks in the Time War, Rassilon sealed them in a rift at the heart of the planet Galen and told the War Doctor that the Daleks had done it. (AUDIO: The Bleeding Heart)

Late into the Time War, Rassilon sent the War Doctor on a mission to find the War Master after he had fled the War. (PROSE: Engines of War)

Advising his past
Rassilon was taken to the Death Zone by Pandoric to offer advice to his younger incarnation in whether to use the Galaxy Eater to destroy the Nestenes. He warned his former self that he would live past his death and that there would be even greater conflicts in his future. (PROSE: Pandoric's Box)

Standing against the Doctor
Rassilon planned to detonate the Tear of Isha in the Tantalus Eye to stop a Dalek plan to wipe Gallifrey and the Time Lords from history. He consulted Borusa on his plan, who told him it would succeed. Rassilon's plan was foiled by the Doctor, who stole Borusa and the Tear of Isha, using Borusa to wipe the Daleks from the Tantalus Eye without killing all life around it. Rassilon condemned the Doctor's actions and made him an enemy of the Time Lords because of it, (PROSE: Engines of War) exiling him from Gallifrey. (PROSE: The Whoniverse)

On the last day of the Time War, Rassilon intended to spare Gallifrey from destruction by using the Ultimate Sanction to turn the Time Lords into beings of pure consciousness to escape the end of creation. The Woman opposed Rassilon's plan to destroy time itself, (TV: The End of Time) along with the Patriarch of the House of Stillhaven. (PROSE: Lords and Masters) Rassilon condemned them to stand behind him in the Panopticon and cover their faces "as monuments of their shame, like the Weeping Angels of old", (TV: The End of Time) and had their names erased from time as further punishment. (PROSE: A Brief History of Time Lords)

Knowing that the Doctor intended to destroy both Time Lords and Daleks by using the Moment, Rassilon contrived to break Gallifrey out of the time-lock that blocked the Last Great Time War from temporal manipulation by implanting a signal into the Master when he looked into the Untempered Schism, and breaching a White-Point Star through the time lock so that could link back to them. He succeeded, with Gallifrey breaking free of the time lock and appearing in the skies above Earth. However, Rassilon was opposed by the Tenth Doctor, who destroyed the White-Point Star to break the link, forcing Gallifrey and the Time Lords back into the Time War. Before Rassilon could retaliate, he was attacked by the Master for revenge once he realised that Rassilon had deliberately driven insane to ensure his plan, ensuring that they were all taken into the time lock. (TV: The End of Time)

Death
Rassilon's battle with caused him to regenerate, (PROSE: Pandoric's Box) reportedly because the Master "shoved White Point Stars down his throat". Rassilon screamed all the way through the regeneration, so much that Ohila had to make him "a special draft of potion" to help. (PROSE: Lords and Masters)

Behind the scenes

 * Timothy Dalton was credited in The End of Time - Part One as "The Narrator", with the name "Rassilon" not being uttered until Part Two, and, even then, only once in his final scene. This title is not actually mentioned in dialogue during The End of Time, nor in any subsequent narrative appearances by Dalton's Rassilon. However, Character Options action figure of Dalton's Rassilon was packaged and marketed under the name of "The Narrator".
 * Patrick Stewart was originally considered for the role.