"Earth will become new Skaro!" - Dalek Jast
Dalek Jast was a Dalek who was part of the Cult of Skaro, a secret Dalek order.
Dalek Jast was one of the four Daleks chosen to become the Cult of Skaro, along with Dalek Thay, Dalek Caan and their leader, Dalek Sec, who began using their initiative to defeat enemies. They were above and beyond the Dalek Emperor himself. During the Last Great Time War they escaped the carnage by hiding between realities in a Void ship, along with the Genesis Ark, which contained an army of imprisoned Daleks.
Their void ship was discovered and taken by Torchwood, a British organization made to fight invading aliens. When the ship opened, Jast and his fellow Daleks along with the Ark emerged during a invaision of five million Cybermen.
During the battle, the Genesis Ark rose and unleashed millions of Daleks on the world. Shortly after, the tenth Doctor and his companion Rose sucked the Daleks and Cybermen back into the void.
Jast and the Cult arrived in New York, Manhatten in the 1930's. The Cult made their base under the Empire state Building still in construction. The Cult kidnapped humans, using them for the final experiment to create Human Dalek Hybrids. Smart humans would become part of the experiment while the less smarter ones became Pig Slaves.
Like Caan and Thay, he had doubts about his leader's choices on preserving the Daleks. Thay protested to Sec about him becoming the first human-Dalek, Jast backed Thay's objections, saying Daleks were supreme and humans were weak. However he assisted nonetheless, injecting Sec with Chromatid 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 the gene feed, Jast took aim at him, ordering him to step away from the controls. Sec ordered Jast to stand down, to be told "He is an enemy of the Daleks, and so are YOU!" 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 beginning 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. When Thay was destroyed, all the new Daleks concentrated on Jast, resulting in his destruction soon after.