Tractite

Tractites were natives of Tractis.

Biology
Tractites had a half-horse, half-ox appearance. They had strange, double-jointed non-human arms, three-fingered hands, and four eyes. (EDA: Genocide)

History
The Earth Empire invaded Tractis, enslaving and killing the Tractites. A few escaped and discovered a Time Tree, which they used to travel to Earth's prehistoric past and prevent humans from evolving, creating an alternate timeline where Earth was known as Paratractis. One Tractite ended up in the 20th century, where he allied with Jacob Hynes.

Both Hynes and the main Tractite force were defeated by the Eighth Doctor, Sam Jones, and Jo Grant. (EDA: Genocide)

The Tractites were one of the species that Professor Hamilton Smith had theories on. (BNA: Dry Pilgrimage)

Tractites were one of the species who had the potential to destroy Gallifrey. (PDA: The Infinity Doctors) Marnal later pondered if they were the species who actually did destroy Gallifrey. (EDA: The Gallifrey Chronicles)