Emperor of the Restoration

The Emperor of the Restoration was the Dalek Emperor who founded the Restoration Empire from the ashes of the Imperial Dalek faction following the close of the Imperial-Renegade Dalek Civil War. He wore a golden casing with a large bulbous dome, deliberately harkening back to the Emperor of the bountiful, unified pre-Civil War Dalek Empire. (PROSE: The Restoration Empire)

According to some accounts, the new Dalek Emperor of the Imperial Daleks then led his people into a time war against Gallifrey, becoming the Dalek Emperor in the Last Great Time War. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe) According to other accounts, however, the Dalek Emperor who led the Dalek Empire following the Civil War, and onwards throughout the Time War, was instead the Dalek Prime himself, who had, in the Civil War, been the ultimate leader of the Renegade Daleks. (AUDIO: Restoration of the Daleks)

Rise from Supreme to Emperor
During the Imperial-Renegade Dalek Civil War (PROSE: The Restoration Empire, TV: Remembrance of the Daleks) the Dalek Supreme who would later become the new Dalek Emperor served on the Dalek Council. After Davros fled the war, he exterminated all other members of the council and appointed himself the new Dalek Emperor. Modelling himself on a former emperor, he built himself a gold casing and augmented his brain capacity. (PROSE: The Restoration Empire)

The Restoration Empire
From this position, he sought to restore the Dalek Empire to its former glory through a new hierarchy of Dalek command and a new system of production. He restored Skaro (PROSE: The Restoration Empire) after it was destroyed by the Seventh Doctor (TV: Remembrance of the Daleks) and overhauled the standard Dalek hierarchy, bringing back Silver Daleks as drones (PROSE: The Restoration Empire) instead of the white-and-gold livery favoured by Davros's Empire. (TV: Remembrance of the Daleks) Also among the Emperor's forces was the Dalek Prime Strategist, a unit who claimed to be older than the Emperor. (COMIC: Defender of the Daleks)

Into the Last Great Time War
According to one account, the new Dalek Emperor continued with Davros's plan for the Imperial Daleks to move against the High Council of the Time Lords, thus leading his armies into the Last Great Time War. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe) This stood in contrast to another account in which the Dalek Emperor in the Last Great Time War was the original Dalek Emperor who once led the Renegades. (AUDIO: Restoration of the Daleks) The Dalek Emperor in the Last Great Time War led his people throughout the War and eventually fell through time (TV: The Parting of the Ways) and the Void (PROSE: The Whoniverse) on the last day of the War with his command ship. He was ultimately slain by Rose Tyler as the Bad Wolf entity. (TV: The Parting of the Ways)

The altered universe
When the Tenth Doctor poisoned the Kotturuh in the Dark Times, (PROSE: The Knight, The Fool and The Dead) he caused fluctuations in time, (PROSE: The Guide to the Dark Times) resulting in the Restoration Empire never fighting the Time War. (COMIC: Defender of the Daleks) The Emperor received a message from an ancient Dalek drone, which he deduced was a survivor of a Time Squad that had yet to be sent back in time. From the message, the Emperor concluded that history was under attack, which the Dalek Empire was vulnerable to, and that the Doctor was involved, but still needed more information. He decided the necessary information could be found somewhere like the Archive of Islos. (PROSE: The Last Message)

The Emperor personally led the Daleks’ invasion of Islos to seize the Archive. However, the Chief Archivian made a deal for the rescue of the Archive, promising their rescuer the Daleks. When the Emperor entered the Archive along with the Strategist and Executioner, they found it empty. The Chief Archivian informed them of its deal as an Entity emerged from a portal. (WC: The Archive of Islos) The Daleks retreated from Islos and returned to Skaro, pursued by the Entity. It attacked Skaro and the Daleks’ firepower proved ineffective, forcing the Emperor to order an evacuation. The Strategist advised that the evacuation was failing and they should abandon the planet. The realisation that the home planet had been lost caused the Emperor to fall silent, forcing the Strategist to coordinate the retreat. After the Strategist suggested reinforcements, the Emperor decreed that the Sentinel of the Fifth Galaxy was required. The Strategist was sent to meet the Sentinel and awaken a dormant army of 10,000 Daleks however the Entity compromised the army and took it over. As the Executioner led Dalek forces against the army, the Strategist advised the Emperor to withdraw again as they could not sustain further losses and defended its failure. (WC: The Sentinel of the Fifth Galaxy)

The Strategist created a plan to deal with the Entity by putting it and another enemy of the Daleks, the Mechanoid Empire, against each other, believing its plan could deal with both rivals. Acting under the plan, the Emperor, planning to make the Mechonoids think that the entire Dalek Empire had been destroyed (WC: Day of Reckoning) by arriving to Mechanus in a damaged saucer with minimal support, travelled to Mechanus and claimed to seek their help. He was greeted by the Queen and taken to her star chamber where they reviewed the conflict. After witnessing his Dalek guards be destroyed by her Mechanoids without any more Daleks coming to their aid, the Queen speculated that he and the Strategist were the only two Daleks left. After the City’s power was drained, the Emperor revealed to the Queen that he’d deliberately led the Entity there. (WC: Planet of the Mechanoids) She demanded to know why and he claimed if the Mechanoids were truly superior they’d be able to stop the Entity. When the Entity arrived it took over a Mechanoid and demanded the Mechanoids surrender the Emperor. The Queen decided if it broke through their defences she would surrender the Emperor. He and the Queen observed the Mechanoids forming a shield around the City and as the Entity began to break through she abandoned him out in the open. The Entity’s attacks hit him numerous times, but he was saved by the efforts of the Strategist and Mechanoid 2150 who used the orbital array to force the Entity back to its original dimension. The Queen ordered him and the Strategist to leave Mechanus, warning them that the Mechanoids were coming for the Daleks. (WC: The Deadly Ally)

Returning to Skaro, the Emperor and Strategist reactivated the City and recalled the Daleks there for the battle they had now manipulated the Mechanoids into. The Mechanoids arrived and were caught off guard by the Emperor’s reinforcements, given that they had been led to believe he and the Strategist were the last. He delighted in the ensuing battle, however proclaimed betrayal upon seeing the Strategist being escorted by the Queen and 2150. After the Strategist betrayed the Mechanoids and sent them through a portal into the Entity’s dimension, the Emperor congratulated him. However he also reminded the Strategist that “superior beings” were harder to manipulate. As the two inspected the battlefield, the Entity briefly possessed a ruined Mechanoid and teased them that they didn’t know what was coming for them. (WC: Day of Reckoning)

Into the Dark Times
At some point after the Mechonoid—Dalek battle, the Daleks faced the threat the Entity had warned them of: (WC: Day of Reckoning) a species from the Dark Times known as the Hond, (COMIC: Defender of the Daleks) who had also been unleashed by the invasion of the Archive of Islos. (PROSE: The Restoration Empire) With Skaro in danger of falling to the Hond, the Prime Strategist suggested to the Emperor that the Doctor be used against the Hond. The Tenth Doctor was captured by the Daleks and brought before the Emperor. He recognised the existence of the Empire he was interacting with, who had never fought in the Last Great Time War, as "a paradox". The Emperor convinced him to help them and sent him to meet the Strategist. Together they discovered a way to pacify the Hond, which they deployed just as they approached Skaro’s defences. Afterwards the Doctor escaped, with the aid of the Thirteenth Doctor, and the Strategist met the furious Emperor. The Strategist defended its failure and suggested the Daleks could use other Doctors, such as the Eighth Doctor. (COMIC: Defender of the Daleks)

Eventually discovering the source of the fluctuations to be the Dark Times, where the Daleks' own timeships could not travel, the Emperor formed a Time Squad to locate an earlier incarnation of the Doctor and use his TARDIS in order to travel back there. (PROSE: The Restoration Empire) The squad's main mission was to rectify the temporal fluctuations to the Daleks’ benefit, or at the very least return the universe to normal. (PROSE: The Guide to the Dark Times, The Restoration Empire)

Behind the scenes

 * Speaking of his portrayal as the Emperor, Nicholas Briggs described him as "high and mighty".