The Dominators were a race of near-Humans who controlled much of the Ten Galaxies.
Biology
The Dominators were similar to Humans in form, but over two and half metres tall with pale skin, dark hair and red-rimmed green eyes. (DWN: The Dominators (novelisation))
Technology
The Dominators used saucer-shaped craft which were powered by negative mass flux absorption. This negative mass flux absorption allowed the ships to absorb radiation and convert it to propulsion.
The Dominators used the Quarks are labourers in their forces. Though they used them for a variety of tasks, they preferred to use slaves where they could, in order to reserve energy.
The Dominators usedNeuro-Initiative Tests, or NIT. These tests are intelligence tests where the subject is shocked and then has to fit objects into similarly shaped holes. These tests are to find out the suitability of other species for slavery. (DWN: The Dominators (novelisation))
History
The Dominators controlled much of the Ten Galaxies, which they took by ruthless, calculated force. Eventually, their Quark forces were stretched thin, which meant they required slaves in order to fill the jobs that the Quarks were taken from. Several planets were researched for this purpose, such as Epsilon Zero Gamma and Dulkis.
The scouts sent to Dulkis consisted of Tobs and Rago. The plan was to take the strongest Dulcians as slaves and then use a special seeding device dropped into the magma of the planet in order to destroy it. This destoryed planet would then have its energy used for powering the Dominator fleet. Though the Dulcians were unwilling to fight back, The Doctor was able to stop them from destroying the planet. (DW: The Dominators)
The Dominators and the Quarks attempted to invade Earth in the late 20th century. Their attempt to use the Earth's core as a fuel source is foiled by UNIT. (DWM: Fires Down Below)