Blue Dalek

Blue Daleks are non-commissioned officers (EDA: War of the Daleks)

Behind the Scenes
A 70s era dalek from the series was repainted blue and placed in the London Madame Tussaud's Wax Museum in 1980 alongside the wax Tom Baker. It featured on the 1983 cover of the Radio Times for the 20th anniversary of Doctor Who.

Indeprod bought it in auction in 2005 and it is currently up for auction again.