Dalek Prime
From TARDIS Index File, the free Doctor Who reference.
The Dalek Prime was a senior-ranking Dalek according to some accounts. The title may have been interchangeable with that of Dalek Supreme, much in the same way that the Supreme was occasionally referred to as the Black Dalek.
References to the Dalek Prime are limited to secondary sources, where it is variously the last survivor of the Daleks created first-hand by Davros, the leader of the Daleks on Skaro (the Supreme commanding off-world operations), and an amalgam of the Supreme and the Dalek Emperor. (DWN: The Chase (novelisation), The Evil of the Daleks (novelisation), EDA: War of the Daleks)
It is commonly shown as a shorter Dalek with a spherical top section, rather like the TV21 Dalek Emperor.
