Cult of Skaro - Dalek Sec

Dalek Sec was the leader of the cult and of the Dalek attack during the Battle of Canary Wharf against the Cybermen. His original casing was black instead of the golden colour traditional Daleks had. He showed his leadership by communicating to the enemy, namely, Rose Tyler, Cybermen and The Doctor, and commanding the other three Daleks. Because there were only four Daleks outside the void, Sec fought alongside the other Cult members against the enemy, and kept checking the status of the Genesis Ark. However, as soon as the Ark was 'primed' Sec escaped the Torchwood tower with the Ark, to command the entire army of Daleks from the sky whilst keeping a close watch on the Ark. Because the Cyberman Army and the Void Ship containing the Cult, the Genesis Ark, and the Dalek Army within had travelled through the void, they had all picked up 'void stuff' which, when the Doctor reversed the flow of the radiation, sucked both armies, the Genesis Ark and the Void Ship back into the Void. Dalek Sec and the Cult were able to escape the slaughter by initiating an Emergency Temporal Shift.

Along with the rest of the Cult of Skaro, he ended up in New York in 1930 and established a base beneath the Empire State Building. Taking control of the Empire State construction and forcibly converting humans into "pig slaves" to serve as a labour force, the Cult of Skaro also worked on experiments designed to evolve Dalek-kind into a new form. The Cult recruited the power-hungry human servant Mr. Diagoras, who seemed to think more like a Dalek than most, which Dalek Caan admitted. Sec turned against the concept of Dalek genetic purity, viewing survival as more important and seeing human DNA as holding useful attributes, as the humans thrive as a species whereas the Daleks had become nearly extinct. Using himself and Mr Diagoras as the test for the Final Experiment, he was transformed into the first Hybrid Dalek.

While in his new body, he began to feel humanity for the first time in his existence, being motivated by emotions rather than the traditional Dalek drive to conquer,saying that Davros,the Dalek's creator was wrong.Motivated by this, Sec asked the Doctor to help him create more hybrids using human bodies. In opposition to the views of Davros, their creator, he decided that the Daleks would have to evolve to survive or eventually die out. When the Doctor said Earth didn't have room for another race Sec said the Doctor could use the Tardis to take the new race to another world. Sec was upset at the death of the Hooverville Leader Solomon who tried to make peace with the Daleks. However, the other three Daleks came to reject Sec's theories and eventually deposed Sec and put him in chains. Dalek Caan took control and fueled the other human bodies with pure Dalek DNA. Sec opposed their attempt to kill the Doctor, warning the others that "If you choose death and destruction... then death and destruction will choose you." The Daleks dismissed this thought and killed their former leader when he tried to protect the Doctor. The Doctor showed his respect for Sec by calling him the "cleverest Dalek ever" and the only one who could have led the Daleks "from the darkness."

Due to his hybridization from Dalek to Human Dalek, Dalek Sec has been the first Dalek to repent the deaths he caused (Dalek Caan being the second), and the only Dalek who willingly sacrificed himself to save the Doctor.

His character as a Dalek/Human hybrid is not entirely clear, as, although he eventually feels humanity, it is sometimes also implied that he still had plans to cause destruction. An example would be when Dalek Caan becomes 'controller' of the Human Daleks; Sec responds to this act of treachery with "That was to be my position!"

Sec was the first Dalek of the new series to have its mutant seen while in a healthy state (with a possible exception of the Dalek Emperor). He was also the first Dalek in the new series to open its lower casing as well, showing longer tentacles. Sec was also shown to be able to engulf Mr. Diagoras in a sack-like membrane projected from what appears to be his mouth parts. His "skin" had a dark-greenish color to it as well.

According to the Doctor Who Files book on the Cult Of Skaro, Dalek Sec was the Commander of the Seventh Incursion Squad and led the attack on the Mechonoids on Magella before being promoted by the Dalek Emperor.