Dalek Executioner (The Guide to the Dark Times)

A Dalek Executioner, also referred to as the Dalek Execution Unit, (AUDIO: The Enemy of My Enemy) was a member of the Dalek Time Squad, a battalion of Time-Sensitive Daleks deployed by the Emperor of the Restoration to investigate numerous divergences in time and manipulate them for the benefit of the Restoration Empire. (PROSE: The Guide to the Dark Times) The divergences investigated by the Dalek Executioner and the Dalek Time Squad had been caused by the Tenth Doctor's attempt to render the Kotturuh extinct during the Kotturuh crisis in the Dark Times. (PROSE: The Knight, The Fool and The Dead)

Physical appearance
The Dalek Executioner's casing resembled those of the silver Dalek drones of the Restoration Empire, but with a black dome and slats. Its black sense globes were ringed with crimson, and its eyestalk's lens likewise glowed red, while its luminosity dischargers were somewhat yellow. Instead of the familiar suction cup, its manipulator arm ended in a three-fingered "claw", with each "finger" resembling the blade of a scythe, (PROSE: The Guide to the Dark Times) and was tipped with a retractable Varga thorn. (PROSE: The Restoration Empire)

Enemy of the Entity
After the Emperor of the Restoration received a transmission from a Dalek drone about temporal anomalies appearing across the universe, (PROSE: The Last Message) the Dalek Executioner oversaw the extermination of the population of Islos during the invasion to seize the Archive of Islos. When the Archivians surrendered, the Executioner accompanied the Emperor and the Dalek Prime Strategist into the Archive, but they found it empty. He demanded to know what the Archivians had done and exterminated all but the Chief Archivian, who explained they had made a deal with an Entity outside of space and time, giving it the Daleks. The Entity emerged from a portal in front of the Daleks (WC: The Archive of Islos) and attacked them, forcing them to flee Islos.

When the Entity followed the Daleks back to Skaro, the Dalek Executioner oversaw the Daleks' attempt to defend Skaro, but reported that their weaponry was ineffective, forcing the Emperor to order an evacuation. After a dormant army awoken by the Prime Strategist to be reinforcements was compromised by the Entity, the Executioner led Dalek forces against them. (WC: The Sentinel of the Fifth Galaxy)

In the Dalek Time Squad
Eventually, the Dalek Executioner became part of the Dalek Time Squad that the Emperor sent to investigate the temporal fluctuations; (PROSE: The Guide to the Dark Times) the Executioner's presence in the Time Squad was part of the Daleks' alternative means of dealing with the anomalies through total extermination. (AUDIO: The Enemy of My Enemy)

The mission to Wrax
When the Dalek Time Squad captured the Eighth Doctor, (AUDIO: He Kills Me, He Kills Me Not) the Dalek Executioner attempted to exterminate him, but was stopped by the Dalek Prime Strategist. The Executioner remained onboard the Dalek Time Ship whilst the Doctor transmatted with the Dalek Time Commander, the Dalek Scientist, the Dalek Prime Strategist and a Dalek drone to Wrax, as they intended to investigate the changes to Wrax's timeline, as well as acquire the Wraxian super weapon - the Devolver. However, when the Time Commander and the Scientist suspected that the Daleks had been betrayed by President Sarathin, the Time Commander ordered the Dalek Executioner to transmat to Wrax with several Dalek drones and exterminate all Wraxians, despite protest from the Prime Strategist. Eventually, the Daleks agreed to the Doctor and Sarathin's deal to leave Wrax in peace, in exchange for the dismantling of the Devolver. However, shortly before the Daleks left Wrax, the Dalek Time Commander secretly sent the Dalek Executioner back to Wrax, who used the Devolver to reduce the Wraxians to single-cell organisms, before returning to the Dalek Time Ship as the Dalek Time Squad prepared to travel to the Dark Times. (AUDIO: The Enemy of My Enemy)

In the Dark Times
The Dalek Executioner was on the bridge of the saucer during the Battle of Mordeela. It swatted the Doctor away when he tried to rein the Daleks in, throwing him against a wall. (PROSE: All Flesh is Grass)

After the Eighth Doctor left the Daleks, the Executioner and the Commander entered a chamber only the two of them could access and received new orders from the Emperor, pre-recorded for the event of the Squad failing to correct the timeline. The Emperor instructed them to destroy Gallifrey to prevent the rise of the Time Lords. (PROSE: Mission to the Known) Referring to the orders as "the Ultimate End", the Executioner and Commander prepared for the attack on Gallifrey. (PROSE: All Flesh is Grass)

Death
After the Dalek Time Ship was forced back into the Time Vortex by the Eighth Doctor, (PROSE: All Flesh is Grass) the Dalek Time Commander granted the Dalek Executioner autonomy to carry out an emergency purge of all aliens aboard to stop the sabotage. However, the Executioner gradually became more insane, damaging the ship and killing other Daleks on its rampage to kill the Doctor and two alien prisoners. The Time Commander was unable to rein it in, to the Dalek Prime Strategist's frustration. The Dalek Executioner attempted to destroy the bulkhead that the Doctor was hiding in, but when the Doctor detonated an explosive he had planted on the Dalek Scientist, the half of the saucer the Dalek Executioner was in was sucked into the Time Vortex, (AUDIO: Mutually Assured Destruction) where it was torn apart by the time winds. It was observed by the Dalek Prime Strategist as he fell through the Vortex, with him noting it was still pointlessly firing its gun. (PROSE: Exit Strategy)

Psychological profile
River Song described the Dalek Executioner as "exceptionally cruel". Adept at torture, it was always willing to inflict pain on other beings to get what it wanted. In battle, it "always shot to kill", to the point that it would sometimes disobey orders for the sake of finishing off an opponent. (PROSE: The Guide to the Dark Times) Like the Special Weapons Daleks that came before it, (PROSE: The Restoration Empire) the Dalek Executioner was insane, having to be controlled by the Dalek Time Commander when it was part of the Dalek Time Squad. However, the Executioner was so obsessed with murder that its other functions could be overridden by its desire to kill, driving it further insane. When the Time Commander broadcast a command to the Dalek Executioner to enter a sequence code, the Executioner simply froze, as such a command contravened its instinct to kill. (AUDIO: Mutually Assured Destruction)

Occupied only with murder, the Dalek Executioner was thought by the Dalek Prime Strategist to be a "thoroughly stupid creature". (PROSE: Exit Strategy)

Behind the scenes

 * Speaking of his portrayal as the Executioner, Nicholas Briggs described him as "completely mad".