The Droideka was an NPC, a sophisticated battle droid that was on Count Dooku's ship when he kidnapped Chancellor Palpatine.
Revelation of the Sith[]
When Obi-Wan and Anakin were looking for Palpatine onboard the dreadnought, they reached a nearby lift when they were attacked by droidekas. One Droideka identified them as Jedi and ordered the others to fire hull piercing rounds and to turn on their laser sword dampers. The lift doors opened behind Obi-Wan and Anakin and they quickly backed into the lift, with the doors shutting out the droidekas.