Kate Yates was a human.
She was hit by a car in 2007 and her Dalek Factor was later activated, giving her enhanced strength and intelligence and blond hair. She developed a hatred of humans. She ended up resurrecting the Dalek from the time capsule that had spread the Dalek Factor in the first place and participated in its plan to use a Time Ring it blackmailed from the Tenth Doctor to travel to the year 500,000,000 where humanity was peaceful and knew nothing of the Daleks. She would then convince the people of that era to give her the raw materials the Dalek needed to rebuild its race.
However, Rose Tyler began reaching out to her 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. Her hair colour returned to normal and she lost all the knowledge the Dalek Factor gave her. Kate returned to her life, her immense debt cleared by the Doctor in thanks, and planned to make something of her life, which had been miserable before. (PROSE: I Am a Dalek)