White was a colour.
The Trickster, who normally wore black, wore a white robe and gloves when he appeared to Peter Dalton. (TV: The Wedding of Sarah Jane Smith)
White was the colour of mourning in India. For this reason, members of the cult which worshipped the Skang also dressed in white. (PROSE: Island of Death)
During the Imperial-Renegade Dalek Civil War, Davros's Imperial Daleks had white casings. (TV: Revelation of the Daleks, Remembrance of the Daleks) A white Dalek was present on Moldox near the close the Last Great Time War. (PROSE: Engines of War) Later, the Supreme Daleks of the New Dalek Paradigm were identified by their white casings. (TV: Victory of the Daleks) A white Dalek was present at the Starbane. (GAME: The Doctor and the Dalek)
Chronovores sometimes appeared as pure-white humanoids. (TV: The Time Monster) Chorodorons had white skin, (PROSE: Dreamstone Moon) as did gelem warriors. (PROSE: Ghosts of India)
The trees in the petrified jungle on Skaro were white, having been turned to stone. (TV: The Daleks)