Dalek Sec
Dalek Sec was first seen in Army of Ghosts (Series 2 : Episode 12) and Doomsday (Series 2 : Episode 13) as the leader of the Cult of Skaro. Dalek Sec was wore black armour as opposed to the normal goldish colour worn by other Daleks. Dalek Sec was the leader of the Cult of Skaro and was therefore in charge of leading the Daleks to survival and victory, tasked with thinking up of new ways to beat the enemies of the Daleks and ensure their continued existence. Prior to being leader of the Cult, Dalek Sec was originally leader of the Seventh Incursion Squad, leading the attack on the Mechonoids on Magella.
The Cult’s first plan involved the Genesis Ark, a Time Lord prison ship used to house imprisoned Daleks during the Time War, stolen by the Cult. Dalek Sec oversaw the operation to open the Genesis Ark and release the Daleks within. Dalek Sec took control of the Genesis Ark once it had been primed ready to command his army that would be released. However, when the Doctor reversed the radiation flow from the Void, sucking the Cybermen, the Daleks, the Genesis Ark and the Cult’s Void ship back into the Void, Dalek Sec and his fellow Cult members performed an “Emergency Temporal Shift” to escape to 1930’s New York. Here, Dalek Sec devised a new way to ensure the continued existence of the Daleks by creating Dalek Hybrids with the humans with a base established underneath the Empire State Building.
Dalek Sec also pioneered the Pig Slaves, forcing humans deemed to have low intelligence by Dalek Caan to convert into the beasts used by the Daleks to carry out their menial tasks. However, Dalek Sec realised that some attributes of human DNA would be useful to mix with Dalek DNA as the humans had thrived for centuries while the Daleks were always close to extinction. Dalek Sec used himself and the human Mr. Diagoras as a test in the final experiment to become the first Dalek Hybrid. As part of being in his new body, Dalek Sec began to experience humanity for the first time, and started to be motivated by emotions rather than the Dalek drive to conquer. Dalek Sec asked the Doctor for help with creating the Dalek Hybrids using human bodies, noting that the Daleks needed to evolve to survive or die out, a theory dismissed by the other three members of the Cult of Skaro. Dalek Caan overthrew Dalek Sec as leader of the Cult and Dalek Sec was put in chains, imprisoned by his former team. Dalek Caan chose to override Dalek Sec’s original plan and fed the Dalek Hybrids with pure Dalek DNA instead before ordering the extermination of the Doctor. Dalek Sec opposed this and warned his former team that “if you choose death and destruction... then death and destruction will choose you.”
Dalek Sec repented for the deaths he had caused after he became a Dalek Hybrid, brought on by his new found humanity, though he still appeared to have plans to conquer with the Dalek Hybrids. When Dalek Thay attempted to exterminate the Doctor, Dalek Sec sacrificed himself and took the blast instead, becoming the first and only Dalek willing to die to save the Doctor. After his death, the Doctor showed his respect to Dalek Sec by calling him the “cleverest Dalek ever” for his realisation about the Daleks needing to evolve to survive.