The Sontaran drone was a type of technology used by the Sontaran Empire.
The Sontarans had at least two models of drones. One type appeared as balls of light roughly the size of a football. These could hover across their environment. They fed information of what they discovered to the soldier who deployed them. (TV: The Last Sontaran) The other type of Drone was larger and shaped like a Sontaran Scout Ship, with two arms to manipulate the environment. They had a similar function and were linked by a network to share information. (COMIC: The Betrothal of Sontar)
Drones were let loose by Commander Kaagh when he crashed on Earth. He used them to distract humans while he attempted to use a radio telescope to bring about the destruction of the world. These drones were later deployed against the "half form" children who were friends to Sarah Jane Smith. They were destroyed by Sarah Jane with her Sonic lipstick. (TV: The Last Sontaran)