Rutan scout

The Rutan Scout was a scout for the Rutan Empire that crash landed on Earth in the early 1900s. It was sent to establish a base with a power source and create a beacon to bring the invasion fleet to Earth.

Having studied all planets in the Sol system, Earth was chosen as the best to serve the Rutan Empire's plot to destroy the Sontarans. The Scout made its way to Fang Rock and infiltrated the lighthouse. There it established the beacon and began to kill the lighthouse keepers and shipwreck survivors one by one. Using recent Rutan technological developments the Scout was able to shape shift and take the form of Reuben and electrocute the others.

After a small talk with the Fourth Doctor the Rutan attempted to take the lighthouse when Leela destroyed it. (DW: Horror of Fang Rock)

Three regenerations later, the Doctor was forgiven by the Rutan Host for killing the Scout. (NA: Shakedown)