Supreme Dalek (Victory of the Daleks)

The first white Supreme Dalek of the New Dalek Paradigm was created as one of five new Dalek types by the Progenitor aboard their last surviving ship above Earth in 1941 when the last three Daleks tricked the Eleventh Doctor into allowing them to activate the Progenitor device.

Creation
The white Supreme Dalek was the first to leave the Progenitor. It ordered the disintegration of the three original Daleks before confronting the Doctor. Later when the Doctor and some fighter planes led by Danny Boy modified by the android Bracewell to fly above the atmosphere safely attacked the Dalek saucer, the Supreme Dalek contacted the Doctor and gave him an ultimatum; either let them go, or witness "the Earth die, screaming." The five new Daleks escaped through a time corridor and went on to rebuild their empire, (TV: Victory of the Daleks) and remained its ultimate leaders until the institution of the Parliament of the Daleks with its Prime Minister. The Supreme Dalek maintained token presence in the Parliament of the Daleks. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)

The Dalek Asylum conundrum
When the Prime Minister made a request to the Eleventh Doctor, Amy Pond and Rory Williams to save the Daleks from the Dalek Asylum, the Supreme Dalek informed the Doctor of the alias the Daleks use to refer to him, "the Predator", and some of the information regarding their mission to the Dalek Asylum. Just as the Parliament was about to destroy it, Oswin Oswald removed any memory of the Doctor from the Daleks' Pathweb from the centre of the Asylum, causing the Supreme Dalek, along with all other members of the Parliament, to forget the Doctor entirely. (TV: Asylum of the Daleks)

The Siege of Trenzalore
When the First Question was transmitted from Trenzalore across the universe after the Eleventh Doctor translated it, (TV: The Time of the Doctor) the Supreme Dalek recognised it as the voice of a Time Lord. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe) After the Daleks regained their memories of the Doctor from converting Tasha Lem into a Dalek puppet, (TV: The Time of the Doctor) the Supreme Dalek exterminated the Prime Minister of the Daleks after deeming it unfit for purpose. Following the Prime Minister's extermination, the Supreme Dalek served as leader of the Daleks throughout the rest of the Siege of Trenzalore. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)

The Supreme Dalek piloted the Parliament of the Daleks to Trenzalore to exterminate the Doctor, but was destroyed, along with all the other Daleks, after the Doctor gained a new regeneration cycle from the Time Lords. (TV: The Time of the Doctor; PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)

Behind the scenes

 * Throughout its appearances in Victory of the Daleks, Asylum of the Daleks and The Time of the Doctor, the Supreme Dalek has a deep voice like that of the Dalek Emperor (TV: The Parting of the Ways) and the red Supreme Dalek (TV: The Stolen Earth/Journey's End) and its lookalike (TV: The Magician's Apprentice). Other white Supreme Daleks, such as Supreme Dalek in The Pandorica Opens and the dying Supreme Dalek in The Wedding of River Song, spoke with a standard Dalek voice.
 * As with its fellow new Daleks, the Supreme Dalek in Victory of the Daleks was depicted with a specially created prop. This prop was later used to portray the Supreme Dalek in The Pandorica Opens and was distressed to portray the dying Supreme Dalek in The Wedding of River Song.
 * The Supreme Dalek in Asylum of the Daleks was depicted using a specially created prop.