Dalek Jast

Dalek Jast was a member of the Cult of Skaro and a participant in the Battle of Canary Wharf in 2007. Jast was the first to realise that the Tenth Doctor was still alive after the arrival of the Cybermen when he noticed the Doctor on a video transmission with the Cyber-Leader. During the time in the sphere chamber Jast activated the awakening process and always monitored the Genesis Ark on its priming consoles until the final stage of the awakening (time travellers using their hand to transmit the universe's background radiation as power supply). He had the highest-pitched voice of the members of the Cult. (DW: Doomsday)

Like Caan and Thay, he had doubts about his leader's choices on preserving the Daleks. This showed when Thay protested to Sec about him becoming the first human-Dalek, backing Thay's objections, saying Daleks were supreme and humans were weak. However he assisted nontheless, injecting Sec with Chromatin solution. Along with Caan and Thay, Jast turned against Sec during the creation of the Dalek-humans. When the Doctor discovered the group had overridden th gene feed, Jast took aim at him, ordering him to step away from the controls. Sec ordered Jast to stand down to be met with "He is an enemy of the Daleks, and so are YOU!" stating Jast had lost his authority. After the Doctor escaped to prevent the Gamma strike, Sec protested that the others had betrayed him. Jast replied that it was Sec who had told them to imagine, resulting in them imagining their leader's irrelevance. At the Laurenzi theatre Jast and Thay confronted the Doctor with the imprisoned Dalek Sec. Thay announced it was the begining of a new age. Jast added Earth would become the new Skaro. When the Dalek-humans questioned their orders after Gallifreyan DNA was mixed with theirs, Thay fired on the new Daleks. Jast instantly supported Thay in the battle. Once Thay was destroyed, all the new Daleks concentrated on Jast, resulting in his destruction soon after. (DW: Evolution of the Daleks)

Personality
He had the highest-pitched voice of the members of the Cult. Jast was highly reserved, only speaking when addressed or when he believed it to be vital to the matter at hand. He was a faithfull servant to Dalek Sec and often stayed at his side during their time at the Empire State Building in 1930, until the cult's rebellion against Sec. (DW: Evolution of the Daleks)

Behind the scenes

 * The original shooting script identified Dalek Jast as Dalek Rabe. The Doctor Who Files and Doctor Who: Battles in Time identify him as such.