Wormhole

A wormhole was a passage which linked two separate points in space-time, usually serving as a shortcut between those two points.

The Swarm traveled from planet to planet through wormholes they created. One of these linked the planets San Helios and Earth, through which the passengers of a London bus (including the Doctor and Lady Christina de Souza) arrived. The wormhole was eventually closed by Professor Malcolm Taylor before most of the Swarm could get through, thus saving the world. These wormholes contained high amounts of dangerous energy and instantly incinerated anything that passes through it. The only way to survive a journey through the wormhole was with a metal shield enclosing the occupants (even a damaged vehicle would suffice). The Swarm could travel through their wormholes due to their metal exoskeletons. (DW: Planet of the Dead)

The Shalka were capable of converting black holes into wormholes. (WC: Scream of the Shalka)

During the Millennium War, the Osirians stopped the Mad Mind of Bophemeral from creating a wormhole in the Horsehead Nebula, which would have killed quintillions. (PDA: The Quantum Archangel)

Phobos had a wormhole located on its surface. (BBCR/BFA: Phobos)

The Daleks utilized a device known as a Oblivion Continuum, which drew power from a captured wormhole. (DW: Victory of the Daleks)

Brox's spaceship began creating wormholes when its engines began to wear out. (DWAM: Nowhere Man)