War droid
From Tardis Wiki, the free Doctor Who reference
A war droid was an armed combat robot which could be contracted to undertake or assist with missions, and stored in a deep freeze when not in use. Their weapons could include rapid-fire plasma guns, timed limpet mines, EMP charges, and electroshock rams.
Artie was a war droid contracted by Vienna Salvatori to help her find and kill the Master. He was disguised as a more menial service robot, and was programmed to explode if his contract were to be vacated, covering up any evidence of his existence or actions. (AUDIO: Prey)
