A Dalek fell to Earth during the 1st Century before it was dug up by young archaeologists. It was stripped of its gun and discovered by the Tenth Doctor.
Kate Yates, hit by a car in 2007 and revived by her Dalek Factor, was given enhanced strength and intelligence and blond hair. She ended up resurrecting the Dalek from the time capsule that had spread the Dalek Factor in the first place. It advanced on the Doctor, chasing him outside before being knocked over the edge of the cliff by a crane. It was still young and gunless, but that didn't stop the Dalek from repelling the Doctor into the sea when he tried to destroy it. The young Dalek attacked the passengers on the train and forced Frank Openshaw, the man who discovered the Dalek, to reattach its gunstick. Openshaw was exterminated after stating the Doctor would stop it. Fully restored, it rampaged through the town before being encountered by Rose and the Doctor. Its plan was to use a Time Ring to travel to the year 500,000,000 where humanity was peaceful and knew nothing of the Daleks.
However, Rose began reaching out to Kate's human side by reminding her of all the good things of humanity. Kate's humanity began to reassert itself and she was able to use her Dalek Factor knowledge to set the Time Ring to self-destruct. With her humanity returned, Kate fled with the Doctor and Rose in the TARDIS as the Time Ring self-destructed, causing a warp implosion that destroyed the Dalek. With the Dalek dead, Kate's Dalek Factor went dormant again as it had been activated in the first place by the Dalek's casing being unearthed. (PROSE: I Am a Dalek)