Gearon
Gearon was a representative of his home galaxy at the Galactic Council on the planet Kembel, who had allied himself with the Daleks in their plan to conquer the Solar System. The huge ship from the planet Gearon was seen landing on Kembel, for the first Council meeting, by Marc Cory and Gordon Lowery. (DW: Mission to the Unknown) He played a minor role in most of the Council meetings. At the final meeting, where Celation opposed Mavic Chen, and Chen tried to take over the leadership of the Council, the delegates physically attacked Chen, prompting Chen to shoot Gearon dead. (DW: The Daleks' Master Plan)
Gearon had a featureless, egg-shaped head and wore a visor. His silver space suit was later replaced with a black space suit. (DW: Mission to the Unknown, The Daleks' Master Plan)
Behind the Scenes
The actor who played Gearon in Mission to the Unknown did not receive a credit, but Johnny Clayton and Len Russell played 'Alien Delegates', while Pat Gorman played a 'Planetarian'. It remains unclear, to date, which of them played Gearon.