Grey

Grey was a colour.

Earth in the 30th century had grey land and grey seas, with grey cities linked by grey highways across grey deserts. (TV: The Mutants)

The Inter Minorians had grey skin, (TV: Carnival of Monsters) as did the Grey Man's race. (PROSE: Falls the Shadow)

When the Third Doctor encountered a new Dalek command structure, Dalek drones were identified by their grey casings. (TV: Day of the Daleks, Frontier in Space, Planet of the Daleks, Destiny of the Daleks)

The Renegade Daleks had grey and black casings. (TV: Resurrection of the Daleks, Revelation of the Daleks, Remembrance of the Daleks)