Lok

Governor Lok was the robotic governor of the prison planet Volag-Noc.

While performing his duties, Lok was imprisoned in a cell by former prisoner Gurney, who had broken back in to take over his job, and attached an inhibitor to the android, preventing him from escaping. The Tenth Doctor and Martha Jones came to the prison. The Doctor was put into the same cell as Lok, and removed his inhibitor. The two then broke out and broke into Gurney's office. Acting on his imperatives, Lok saw fit that the prison should be sterilised, killing the prisoners, believing Gurney's actions have shown him that 'they are beyond rehabilitation'. The Doctor dissuaded him from this course by cancelling the sterilisation. Lok was shot by Gurney, but the Doctor later reveals that he reprogrammed him during his time on Volag-Noc. (TV: The Infinite Quest)