The Gantacians were an intelligent humanoid species from the planet Gantac. They were tall and lean, and wore bones through their noses. They used electrified batons as weapons. Their leader was the Great Yaga.
In 1992 they invaded and conquered Earth, searching for the Fabled Treasure of Zantar Wrouth. The Seventh Doctor informed Yaga that the Treasure was a planet-sized diamond on the other end of the galaxy. Yaga decided to eat the Doctor anyway, and his new friend Leapy tried to save him. The fleas on Leapy were attracted to the large amount of blood in Yaga and jumped onto him. Yaga, thinking he was being attacked by invisible enemies, ordered his troops to fire on him. This resulted in Yaga's death, which caused all the Gantacians to die as well. (COMIC: Invaders from Gantac!)