Quark

Quarks were originally the robot servants of the Dominators. The Doctor and his companions encountered some of them on Dulkis. (DW: The Dominators)

After being reunited with Jamie McCrimmon in Scotland, the Doctor defeated an attempted Quark invasion of Earth. (TVC: Invasion of the Quarks)

Shortly afterwards, the Quarks used their Giant Wasps to attack the Doctor and Jamie on the planet Gano. (TVC: The Killer Wasps)

On an unnamed jungle world, the Quarks attacked the Doctor and Jamie again, causing his TARDIS to be buried under rubble. (TVC: Jungle of Doom)

In 1971, the Quarks caused the Martha series of robots, which were invented by the Doctor to do housework, to turn against humanity as a prelude to their invasion. (TVC: Martha the Mechanical Housemaid)

In 2044, the Quarks arrived on the planet Hekton to kill the Doctor, but were defeated by the human colonists. (TVC: The Duellists)

In 2053, a Quark pursued the Doctor when he participated in an automobile race on Earth. (TVC: Death Race)

The Doctor and Mel also defeated the Quarks and their Giant Wasps. (MA: Millennial Rites)


 * Since the Dominators were not mentioned in the Quarks' later appearances, it can be assumed that they eventually left them to form their own empire.