Baran

Baran was an officer in the Thal military and, in effect, the first Dalek.

Profile
He was assigned to infiltrate Kaled military headquarters and uncover their secret plans. He encountered Davros while posing as a Muto shortly before he was captured by a Thal squad. He discovered Davros' genetic experiments, but was captured by Nyder.

Davros, recognising him as a Thal spy, made Baran the subject of his next operation, the first to be performed on a Thal. After irradiating and augmenting the brain, Davros had it transplanted into a Mark I travel machine, thus creating the first prototype Dalek. (BFD: Guilt)

Behind the scenes
Nicholas Briggs, who played the part of Baran, currently serves as the voice actor handling the Daleks' dialouge.