G'fras and M'dak were Pakhars who attended the collision of the asteroid Maleficent with Uranus. The Seventh Doctor called them "wonderful gossips". Melanie Bush spent an hour with them while the Doctor was busy elsewhere.
M'dak and G'fras were behind the sabotage of Maleficent, working for a "higher power", according to the Doctor. (PROSE: Uranus)