Blue Dalek

Blue Daleks had several different connotations throughout Dalek history, typically holding a rank superior to normal Dalek drones. It sometimes indicated a normal officer rank, but also had a track record of being associated with time travel experts.

History
During the 2150s Dalek invasion of Earth, a at least one Blue Chrono-Dalek was at the disposal of the Red Dalek. The Blue Chrono-Dalek was capable of acting alone and following the Daleks' enemy through time; (TV: Susan and the Daleks) time travel at that point in Dalek history was in its infancy, with its existence being beyond the understanding of ordinary drones. (AUDIO: The Mutant Phase)

Some of the Humanised Daleks who lived in Alpha's colony on the planet Kyrol following the Dalek Civil War were Blue Daleks. (COMIC: Children of the Revolution)

The Eighth Doctor told Sam Jones that in the Dalek Prime's Empire, Blue Daleks were Daleks bred to be non-commissioned officers. Slightly smarter than the grey Warrior Daleks but without the higher-ranking Red Daleks, Black Daleks and Gold Daleks' levels of autonomy, they served as the equivalent of sergeants and corporals. The Eighth Doctor told Sam this when she asked about the differently coloured Daleks milling about their city, some of which were blue.

During a trial of Davros conducted to root out traitors who sided with him, Blue and Red Daleks filled the room back to the walls behind the higher ranking Daleks. In the ensuing war a Blue Dalek in Davros' resistance was in command of a detail that was setting up bombs in the lift shafts to destabilise the structure of the city's control centre building. Under fire from the Dalek Prime's forces he continued to work on priming the first bomb but as the Daleks beside him were killed he made the decision to abort the countdown and detonate the bombs. The structure was weakened but remained intact. (PROSE: War of the Daleks)

The Dalek Time Controller had a blue casing. (AUDIO: To the Death, X and the Daleks)

During the Last Great Time War, the Dalek members of the Eternity Circle were mostly blue, with silver domes and globes. Other Daleks present at the Daleks' temporary base in the city of Andor on Moldox were silver with blue domes. (PROSE: Engines of War) During the war, the Daleks of the Dalek Scientific Division were denoted by blue domes and sense globes. (AUDIO: A Thing of Guile)

After the Time War, Strategist Daleks of the New Dalek Paradigm were identified by their blue casings. (TV: Victory of the Daleks) As a result of the many failures of the original New Paradigm Supreme, the original Strategist was reduced to a token presence in the Parliament of the Daleks. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)

The reconstructed casing of one Dalek reconnaissance scout, though heavily rusted, bore faded light blue paint on its dome, grating section, weapons platform and sense globes. (TV: Resolution)

Merchandise

 * Dapol, which produced a range of toys based on the classic series of Doctor Who, released several original blue Dalek variants which did not appear on-screen.
 * W008-MOSV was blue with gold details including a claw manipulator arm.
 * A "Millennium Dalek" (W008-M1) had a sparkly blue body with a golden neck grille, slats and sense globes.
 * For the Video Gift Set release of The Five Doctors, an exclusive Dapol action figure was made similar to the Tussauds Dalek color scheme.

Invalid sources

 * The King Dalek was supported by Golden Dalek Guards whose casings sported a head section and shoulder platform "arms" coloured blue. (NOTVALID: War of the Daleks)

Other matters

 * The Dalek Time Controller was originally promoted as being red (DWM 411) before appearing on audio covers.
 * The War Machine Dalek design used in Dr. Who and the Daleks (who also appeared in TV Century 21 and had a black-and-white TV cameo in The Chase) was partially blue instead of silver.
 * A sky blue Dalek with silver sense globes was made at the Madame Tussauds' Doctor Who exhibition and appeared on the back of the Radio Times 20th Anniversary Special. Another partly sky blue Dalek appeared on Pebble Mill at One with Peter Davison cast as the new Doctor.
 * In The Doctor and the Dalek, the player has the option to turn Lumpy's casing blue, among other colours, during simulations. However, it reverts to its original bronze colour after the simulation is completed.
 * In Dalek Hack, the player has the option to turn a Dalek's casing blue, shaped identically to the bronze Dalek but matching the Strategist Dalek of the New Dalek Paradigm.