Red Dalek

Before the Last Great Time War Red Daleks were a type of Dalek bred for intermediate roles between the less intelligent Blue Daleks and the Daleks that served as their immediate superiors, the Black Daleks. Unlike Blue Daleks, they were capable of independent thought, allowing some measure of independent action. (EDA: War of the Daleks) Like Black Daleks they were capable of holding the rank of Supreme Controller. (BFDE: "Death to the Daleks!")

Early history
The earliest known Red Dalek was in charge of the construction of the Sky Seven Space Station when the Mechanoids made their opening volleys in their war with the Daleks. The Red Dalek Leader spared the life of a raving mad Dalek because he correctly believed it was tied to the detected transmissions of alien signals. He located and exposed a camouflaged Mechanoid Interceptor and destroyed it before it could flee. Two more Interceptors arrived, both protected by force fields. He ordered the Daleks to retreat but his Dalek Flying Saucer was melted as he screamed about the heat and the light. (TV21: Eve of War)

Following the destruction of Skardal, a Red Dalek was with the Dalek Emperor as he watched the Terrorkons run rampant. The Red Dalek suggested they simply kill off the Terrorkons, but the Emperor told him the Terrorkons were part of the city's defence system and simply had to be constantly outwitted. When a lone Terrorkon stole a missile powerful enough to destroy the city, the Emperor took the Red Dalek with him to stop it. Reaching the caves in the mountains through the pipe systems, they found the missile activated and close to detonation. The Red Dalek defused the missile. (TV21: The Terrorkon Harvest)

Other red Daleks
Numerous Daleks have been red unrelated to this caste system. Zeg's casing changed colour during an accident in an engineering lab. (TV21: Duel of the Daleks) Storm-Blast Daleks were red. (DAN: City of the Daleks) Some Daleks were also covered with red lead to resist corrosion on planets with humid environments like Venus. (DWAN: Red for Danger)

Among the Daleks of Azhra Korr, the First-Born, Alpha, had a red casing, although his role and his title were more akin to that of the Dalek Prime on Skaro. (DWM: Children of the Revolution) A race of Daleks newly created from Davros' cells after the time war were led by the red Supreme Dalek who also was the highest ranking among his Daleks. (DW: The Stolen Earth) In the New Dalek Paradigm, the red Drone Daleks were the lowest ranked. (DW: Victory of the Daleks)