Zor was the leader and nerve-centre of the Pescatons. He was larger than others of his kind, with an enlarged, oval-shaped head, metallic scales and glowing emerald eyes. He had the power of hypnotism.
In the 15th century, Zor brought the Doctor's TARDIS to the dying Pesca so that the Fourth Doctor could help his people find a new planet. When he refused, Zor faced him in mental combat and was defeated.
In the late 20th century, Zor led the Pescaton invasion of Earth, directing their attacks on London from his base in a sewer. The Doctor set a trap for Zor, subjecting him to high-pitched noise which killed him. With Zor dead, the Pescaton invasion fails. (AUDIO: Doctor Who and the Pescatons)