Lumpy

"Lumpy" was a corrupted Dalek, left in a state of goodness after being interrogated by two Cybermen. When being rescued by the Twelfth Doctor, he tagged along for a mission throughout Telos, Sontar and the Starbane. (GAME: The Doctor and the Dalek)

Behind the scenes
Lumpy shares many similarities with Rusty from Into the Dalek. Both were named by the Twelfth Doctor and both claimed to have turned against their race after their nature was altered. Both Daleks appeared in stories written by Phil Ford.