Dalek Prime

The Dalek Prime, possibly alternatively known as the Prime Dalek (AUDIO: The Thousand Worlds), was, according to some accounts, a senior-ranking Dalek and an alternative form of the Dalek Emperor. The title seemed interchangeable, much in the same way the Supreme Dalek was occasionally referred to as "the Black Dalek". Some accounts considered "Dalek Prime" to merely be a title, whereas others spoke of the Dalek Prime as a unique individual with far-reaching influence throughout Dalek history.

History
According to one account, the Dalek Prime was the earliest Dalek in existence and the one that fired on Davros when they turned on him at their creation. The Dalek Prime was responsible for the advancement of the Dalek race, and the Prime became the ancestor of numerous Daleks. (TV: Genesis of the Daleks, PROSE: The Evil of the Daleks, War of the Daleks)

Following the end of the Thousand Year War, the Dalek Prime began conducting experiments on other life-forms on Skaro, creating mutations which went on to inhabit the petrified jungle and the Lake of Mutations near the foot of the Drammankin Mountains. Eventually the Dalek Prime discovered the molecules that had the ability to cause further mutation within a Dalek and created a drug from its research which would initiate the mutation. Not prepared to test the drug on any Dalek in case it grew beyond its capabilities, the Dalek Prime used the drug on himself and evolved to the peak of Dalek evolution with hugely enhanced mental powers and he proclaimed himself the Emperor of the Dalek race. (PROSE: The Evil of the Daleks)

At one point in their history, the Dalek Prime sent a squad of Daleks in a time machine to pursue the TARDIS and kill the Doctor and his companions. The Supreme Dalek supervised the operation and was to report their progress to the Dalek Prime. The squad ultimately failed. (PROSE: The Chase)

In the year 4000, the Daleks constructed a base on the planet Kembel and formed an alliance with the rulers of the Outer Galaxies to gather the resources they needed to build the Time Destructor which they planned to use to wipe out the entire Solar System. The Dalek Prime awaited the completion of the invasion on Skaro. Due to the interference of the First Doctor, the Time Destructor's taranium core was stolen. The Dalek Prime sent a Red Dalek from Skaro to Kembel in another time machine to aid in its recovery. When the taranium was recovered and returned to Kembel, the Doctor got hold of the Time Destructor and wiped out the Dalek force stationed there. The Dalek Prime, unable to replace the invasion fleet and the Black Dalek commanding it, was forced to accept the defeat. (PROSE: Mission to the Unknown/The Mutation of Time)

In the wake of the Time Destructor disaster, much of the galaxy was warned about the Dalek plan and several war forces — among them the Thals, the Draconians and the Terran Federation — were formed to battle the Dalek Empire in a series of wars fought over the course of the millennium and into the 5000s. It was eventually predicted by Dalek computers that the race would become extinct within 80 years if it could not secure victory. The Dalek Prime took on the title of the Dalek Emperor during this time and, desperate to win, ordered the Daleks to conduct research into the Dalek Factor. He was heavily damaged, presumed dead, when the Second Doctor infected many of the Daleks with the Human Factor, sparking a devastating civil war between them and the Emperor's Guards. (PROSE: The Evil of the Daleks)

Much later, the Dalek Prime returned following the Imperial-Renegade Dalek Civil War and set about planning to extinguish the remaining support Davros still had within the Dalek Empire. A deal was made with a group of Thals who kidnapped Davros, along with the Eighth Doctor, and they transported him to Skaro to stand trial. Before the trial, the Dalek Prime claimed to the Doctor that much of Dalek history was a fabrication to prevent destruction of Skaro by Davros and the Seventh Doctor at the culmination of the Shoreditch Incident. During Davros's trial, one of Davros's supporters destroyed a decoy of the Dalek Prime, igniting another civil war. The Dalek Prime claimed victory after Davros's capture and apparent execution and after his supporters were apparently wiped out. (PROSE: War of the Daleks)

Another Dalek Prime
According to another account, the battle of Pejorica, fought between the Daleks and the Jariden, occurred at a point in Dalek history prior to the creation of a Dalek Prime encountered by the Doctor in command of a ship. Travelling back in time, this Dalek Prime was able to take control of the earlier versions of the Daleks fighting in the battle; they didn't know about his existence and rank. This account referred to Dalek Primes as an advanced form and rank of Dalek, rather than a singular individual.

The time-travelling Dalek Prime, pulled through the Doctor's timestream and encountering the fifth, sixth, seventh and eighth incarnations of the Doctor, was finally trapped in a time loop created by the Fifth Doctor. (AUDIO: The Four Doctors)

Other references
The Master once called the Dalek Prime "ridiculous". (PROSE: Legacy of the Daleks)

During the Last Great Time War, the War Doctor stated that he never heard of the designation Prime Dalek, who may have been another rank, given the likely coexistence with an Emperor. (AUDIO: The Thousand Worlds)

Behind the scenes

 * The Dalek Prime's original appearance was to be the War of the Daleks TV serial proposed by John Peel. The story was never produced following the show's cancellation in 1989. Peel kept the idea and the Dalek Prime appeared or was mentioned in all of his Dalek novels and novelisations apart from The Power of the Daleks. The audio story The Four Doctors marks the Dalek Prime's only appearance in a story that was neither a novel nor written by Peel (excluding Genesis of the Daleks since it was originally a standard Dalek before future writers came up with the concept of a Dalek Prime).
 * Though they have not been formally identified, the Dalek Prime shares both appearance (as a golden Dalek with a spherical top section) and origin story (as the very first Dalek ever created who later rose to the top of Dalek hierarchy) with the Golden Emperor, the first Dalek Emperor described in The Dalek Chronicles.
 * Novels usually refer to the Dalek Prime as a "he" rather than an "it" like all the other standard Daleks. This would also happen with Dalek X in the novel Prisoner of the Daleks.
 * Depending on the player's progress, "Dalek Prime" is a potential rank for the Metaltron to attain in the video game NOTVALID: The Last Dalek.