Flying saucer

Flying saucers are a form of disc-shaped spacecraft which have been used by many species throughout the Universe for many millennia. The term "flying saucer" was also often used as a joking synonym for alien spacecraft by Humans, like "Martian" for any kind of alien.

Dominator flying saucers
Flying saucers were also used by the Dominators in their fleet. They were powered by negative mass flux absorption, where their ships could absorb radiation and convert it into propulsion. (DW: The Dominators)

Cyberman flying saucers
The Cybermen used a saucer-shaped landing craft to land on the Moon in 2070. (DW: The Moonbase)

Adiposian Nursery Ships
The Adipose used Nursery Ships to carry young Adipose from the planet on which they were seeded to the Adipose homeworld. They were large enough to carry several million Adipose and were equipped with levitation beams to transport the Adipose safely from the planet's surface into the craft. (DW: Partners in Crime)

Jathaa Sungliders
These saucer-like crafts, apparently capable of interstellar travel and possesing powerful weapon systems, seemed to be the main mode of transportation for the Jathaa when visiting Earth. (DW: Army of Ghosts, TW: End of Days).

Behind the Scenes
Flying saucers are the stereotypical alien spaceship in the real world, being first reported in June 1947 (and having a history of similar forms recorded in tapestries and paintings) and appearing in science fiction and alleged real world sightings since.