Davros

Davros is the creator of the Daleks. He serves as the main antagonist of Season 1 and Season 18, the secondary antagonist of Season 2 and a recurring antagonist throughout the rest of the series.

Abilities
Davros has a huge army of Daleks at his beck and call. He can also shoot bolts of electricity from his metal hand. On his chair, he has several levers and buttons which he can press to use to move his chair and turn on lights around his castle. He also has a button which controls his life support systems. If it's pressed for any more than 30 seconds, he will die.

In the Seventh episode of Season 7, he becomes a Dalek Emperor. He spends the rest of this season - as well as seasons 8 & 9 - in the Dalek casing, before going back to his chair in Season 10.