Flying saucer

Flying saucers are a form of disc-shaped spacecraft which have been used by many species throughout the Universe for many millennia. On pre-first contact Earth, it was often used as a general term for alien spacecraft, much the same way the term Martian was used for any kind of alien. In this meaning, it was more or less interchangable with the term UFO

Dalek flying saucers
During their history the Daleks made extensive use of flying saucers of several types. During the 22nd century Dalek invasion of Earth made use of saucers for planetary transport. (DW: The Dalek Invasion of Earth). During the Last Great Time War the Daleks fleet consisted of about ten million, including the Dalek Emperor's flagship.

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).

Nedenah Flying Saucers
The Nedenah were a species of explorers that frequently visited Earth using flying saucers. These were large, featureless, pale-coloured disks. They were capable of moving 30 times the speed of sound, could stop in a second and were highly manoeuvrable. Though they were opaque without any windows, the Nedenah would navigate by the ship telepathically beaming the view from outside. The hull could also be shed if it was damaged, leaving an undamaged hull underneath. (PDA: The Devil Goblins from Neptune)

One of their crafts crashed near Roswell in 1947, and was salvaged by the United States Army, who reversed engeneered many technologies from it. (PDA: The Devil Goblins from Neptune)

Krillitane Craft
During the 2007 Krillitane infiltration of Deffry Vale High School in London saucer-like craft presumably connected with them were spotted in the area.

Foo Fighters
In 1945 the Doctor witnissed a jellyfish-like saucer craft he explained to be the source of the Foo Fighter rumours amongst air force pilots of the time. It was piloted by a pilot of an unnamed species. (PDA: Atom Bomb Blues)

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.