Eternal Dalek

The Eternal Dalek was one of the new species of Dalek that emerged from the Progenitor in 1941. It worked some of the machinery inside the Dalek ship and escaped through the time corridor with the Supreme Dalek, Strategist Dalek, Drone Dalek and Scientist Dalek. (DW: Victory of the Daleks)

Behind the scenes
The Eternal's name was given by Steven Moffat in Doctor Who Confidential.

Steven Moffat wanted to try and create a episode story based on the name.