Beaus

The Master of Beaus or simply Beaus was a Galactic Council member.

Profile
He had apparently been persuaded to join the alliance by Zephon. By remaining low-key at the meetings, he survived until the final meeting, where he strongly challenged Mavic Chen, and was then imprisoned by the Daleks. With Celation, Mavic Chen and Malpha, the remaining members of the Council, he agreed to go back to his own people and warn them about the Daleks' invasion plans and to fight against them, upon their escape from Kembel. (DW: The Daleks' Master Plan)

Beaus, a tall alien, his face indistinguishable due to the dark visor and chlorine fumes he breathed, wore a protective suit and his helmet had an antenna on top.

Behind the Scenes
The actor who played Beaus in Mission to the Unknown did not receive a credit, but Sam Mansary played an 'Alien Delegate', and is of African descent, which match the still shots from the episode appear to show a dark-skinned actor inside Beaus' space suit.