Dalek Caan comes from the Planet of Skaro and was created by the Dalek Emperor to find new ways of recreating their species. He wasn't the Leader of the Cult of Skaro Dalek Sec was until they went back in time to Manhatten when the Empire State Building was finished completion. When Dalek Sec Hybrid turned into a nice Dalek then Caan chained him up and then Daleks Thay and Jast had Killed Sec. Caan technology is a Blaster and a Millitary Computer.
When they first appeared the Cult of Skaro were inside the Sphere that came out of the Void which the Cybermen had followed. Then when the Cybermen called an Alliance they had said no. Then the Battle of Canary Wharf had began inside Torchwood Tower. Daleks Vs Cybermen so Caan followed his Dalek friends which had killed a lot of the cybermen because they were made out of Dalekanium. When the Daleks and Cybermen were sucked into the Void Caan Emergency Temperal Shifted along with Sec, Thay and Jast.
When the teleported they ended up in New York 1930s. They had stolen humans from a poor place called Hooverville. If they were smart they would be part of the final experiment if not they were turned into Pig Slaves Part Human Part Pig. When the Doctor and Martha got into the Cult of Skaros lair the Final Experiment which Dalek Sec wanted the last of their species to Evolve into Part Dalek Part Human. When Sec turned into that Caan and the others thought he was turning more Human and Dalek. So Dalek Caan and Dalek Jast headed towards Hooverville because the Doctor escaped. When they got there a man named Solomon had stood up and talked to them. Caan then Exterminated him with one shot so when the Doctor almost got Exterminated Sec told them to hold their fire and bring him to him. When the returned moments later Dalek Caan had turned against Dalek Sec Hybrid. Daleks Thay and Jast turned on Sec too so that the Human Daleks were 100% Dalek. Sec was then chained up an the Human Daleks were born. Then the Doctor sent a signal to them so some of the Human Daleks went to the Theatre with Daleks Thay and Jast who had Dalek Sec Hybrid Chained to them. Moments later Thay had shot Dalek Sec and Killed him. The Doctor thought that was the only Dalek who could have taken them to another place. Then the Doctor had made the Human Daleks turn on their Masters. Then some of the Dalek Humans were Exterminated and so were Dalek Thay and Dalek Jast. Caan then killed every Human Dalek and when the Doctor met Dalek Caan last survivor of the Dalek Race he Emergency Temperal Shifted.
Years Later Caan returned and he brought back a Dead Dalek Creator Davros Lord and Creator of the Daleks. They were inside the Crucible and Dalek Caan was Left with not protective Armor where his Mutant was. Caan managed to get into the Time War but the Time War was Time Locked. This made Caan got mad and he could see the Future. They had stolen 27 Planets like Clom, Adipose 3, Pyrovilia, The Lost Moon of Poosh, Earth and many more. With a New Dalek Empire they had Killed so many Huans on Earth so they were the Masters of Earth. The Supreme Dalek called Caan The Abomination. When the Doctor and his Children of Time were on the Crucible Dalek Caan told the Doctor one of his Companions would Die. When Donna now part Time Lord arrived with a Duplicate of the Doctor they had stopped the Reality Bomb, Killed the Supreme Dalek and made the Daleks Weaponless and Spinning around. But the Duplicate Doctor had Destroyed the Dalek Race and the Crucible was about to Blow Up. It turned out to be that Dalek Caan betrayed his own Race and Davros. When all of the Doctor's Children of Time went inside the Doctor said to Davros come with me but Davros said it was all the Doctor's fault he Destroyed the Dalek Race so he blamed the Doctor. Caan's last words were one of them will die. So when the Tardis left the Crucible it Blew up and took Earth back to it's right possition. Caan was right one of them it was Donna so her memory was erased with her journey's as the Doctor's Companion.
He has appeared in Series 2: Army of Ghosts and Doomsday
Series 3: Daleks in Manhatten and Evolution of the Daleks
Series 4: The Stolen Earth and Journey's End