Ptolem

	Thal
	Scientist
	The Mutant Phase
	Christopher Blake

Professor Ptolem was the Thal scientist in charge of the Dalek research into the Mutant Phase, as they thought any contact with it would affect them. With help from the Fifth Doctor and Nyssa, he discovered the cause of the Mutant Phase, then travelled back through time to complete the research. (AUDIO: The Mutant Phase)