Trodos

Trodos was the home world of the Trods. In 2066, the Trods enslaved the Human population on Trodos, but were defeated by the Doctor. (TVC: The Trodos Tyranny)

Some time later, a space traveler came to Trodos and reactivated the Trods. (TVC: Return of the Trods)

Centuries later, the Daleks invaded Trodos and massacred most of the Trods, but were defeated by the Doctor. (TVC: The Trodos Ambush)