Emperor's Personal Guard (The Witch's Familiar)
From Tardis Wiki, the free Doctor Who reference
An Elite Guard Dalek was among the many types of Daleks inside the Dalek City at the time of the Twelfth Doctor's visit and was among those that cornered Missy. Distinguished as ever by a black dome, the guard appeared as a variant of the Skaro City Dalek model with a light blue middle section, and a blue eye lens as seen on bronze Daleks. (TV: The Witch's Familiar)