Due to the temporally unstable nature of Dalek history, establishing who their primary leadership are can get a little confusing. Between Dalek Emperors, Supreme Daleks, Dalek Parliaments and interference from their creator Davros, the Daleks have had numerous rulers or ruling bodies over their corrupted history.

However, one concept that has remained constant throughout most of the Dalek timeline is the concept of the Dalek Supreme Council, a ruling body that served directly under the Emperor. This concept was perhaps best expressed in the Third Doctor story Planet of the Daleks, with the black and gold Supreme Dalek being a representative of the Dalek Supreme Council. The idea was later elaborated upon in the Big Finish audio We Are The Daleks, in which the Dalek Emperor summons the Supreme Council to preside over the Doctor’s execution.
Although the concept of the Dalek Supreme Council is fairly well-established, which unique Daleks actually make up this council remain mostly a mystery. Other than the Supreme Dalek seen in Planet of the Daleks there has been no reference to specific members of the Council on-screen. As the Doctor Who fanbase is known for speculation, however, there have been several theories as to which Daleks feature on the Council.
The Dalek Supremes

Undoubtedly the primary members of the Dalek Supreme Council were the various Dalek Supremes that were active during Dalek history. Although Dalek Supremes vary in design and colour schemes, and it is unlikely that all Supreme Daleks were members of the council at once, it seems only logical that the Dalek Supreme Council was made up of Supreme Daleks. There are various distinct Supremes from across Dalek history, from the Gold Daleks of Jon Pertwee’s era to the Black Daleks that ruled in the 1980s.

The most likely candidates for inclusion on the Supreme Council include the commander-class Daleks of the early Dalek empire – identified by the black base colour of their casings, replacing the standard silver. Later Supreme Daleks include the previously mentioned Gold Daleks and Black and Gold Supreme, the Black and White Supreme featured in Resurrection of the Daleks, and the Black and Silver Supreme featured in Remembrance of the Daleks. Although counted as Supreme Daleks, the red New Series Supreme as well as the White Paradigm Supreme are unlikely to qualify, as their post-Time War placement in Dalek chronology means they outlast the Council itself.
Whilst there are probably dozens, if not hundreds of Supreme Daleks, there are likely others that make up the Supreme Council. The Big Finish audios have proven that Daleks would often specialise certain members of their ranks for particular roles, and the same is true of their upper echelons of command. Whilst the Supreme Daleks would have made up the majority of the Council, these Daleks are a more elite caste designed for the development of special weapons, secret strategies and temporal machinations.
The Eternity Circle

First mentioned in the War Doctor novel Engines of War, the Eternity Circle were an elite group of five Daleks sported blue and silver casings that were tasked with creating temporal weapons for use against the Time Lords during the Last Great Time War. These Daleks possessed abilities above and beyond that of a standard Dalek, capable of temporal engineering, advanced reasoning, and even laughter.
Though it may be an error, some are described as being blue and gold, suggesting that not all in the order possess the same markings. However, the recent release of the Dalek Interrogator Prime figure in the B&M Exclusive Doctor and Dalek Figure two-pack suggests that the Blue and Silver colour scheme was not exclusive to the Eternity Circle either, as the Dalek Interrogator Prime from the Big Finish audio In the Garden of Death is apparently depicted with this colour scheme too.
As they form a key component in the Dalek war effort, as well as possessing capabilities above that of the standard Dalek, it is highly likely that the Eternity Circle were also granted seats on the Dalek Supreme Council. Likewise, high-ranking individuals such as the Dalek Interrogator Prime were also likely granted seats on the Council, as they would likely deliver important information to the Council first-hand.
The Cult of Skaro

Although they were only part of the main Dalek Empire for a relatively short amount of time, the Cult of Skaro – an elite order of Daleks capable of imagination – were commissioned by the Emperor to create strategies and long-term survival plans during the waning days of the Last Great Time War.
Due to their high status among the Dalek ranks, allegedly ‘above and beyond’ the Emperor, the Cult of Skaro were likely privy to Supreme Council meetings, and would likely offer their insight into battle strategy or survival tactics. It is known that before the end of the war the Cult of Skaro served as front line commanders before fleeing the war in their Void Ship, meaning their tenure over the Supreme Council was likely very brief, even by Time War standards.
Interestingly, as mentioned in a previous Dalek theories post detailing a possible appearance from Dalek Sec in the Series 9 two-parter The Magician’s Apprentice and The Witch’s Familiar, it is possible that the temporal nature of the Cult of Skaro allowed them to preside over multiple incarnations of the Dalek Supreme Council throughout Dalek history, though this is merely speculation.