Gron

Squadron Commander Gron was the Sontaran who was sent to Earth to search for Field Major Styre. He searched Earth, occasionally picking up radio interference from humans who knew about the Sontaran Empire. After finding a book about Sontarans called Doctor Who and the Time Warrior and failing to find Styre he radioed high command suggesting that humans were dangerous and an invasion should begin. He was later seen with the invasion force. (HOMEVID: Built for War)