Krakanord

The Krakanord was a cybernetically-augmented, insectoid creature. Its shell was armed with an energy weapon, "deadly buzzsaws, capable of slicing the hardest of materials", and an acid blaster.

It was enlisted by the Abzorbaloff to aid in his scheme to get revenge on the Tenth Doctor for his son's death, but turned on its Abzorbalovian employer in revenge after the Abzorbaloff made him wait in their hideout for three months, feeding it nothing but Earth food, which the Krakanord found disgusting. Once it had melted the Abzorbaloff with its mechanical shell's built-in energy weapon, the Krakanord prepared to initiate a plan to take over the Earth, but was stopped by the Doctor, who highjacked the Abzorbaloff's transmat circuitry to send the Krakanord to Clom. As it teleported away, the Krakanord vowed revenge on the Doctor. (WC: The Genuine Article)