Wormhole

A wormhole was a passage which linked two separate points in space-time, usually serving as a shortcut between those two points allowing two distant points to be drawn together closer. Wormholes could also form between universes in the same multiverse.

Features
Wormholes would disintegrate organic matter. The only way to survive a journey through the wormhole was with a metal shield enclosing the occupants, acting as a Faraday cage. They could also be used as two-way travel. (TV: Planet of the Dead)

Vodium naturally produced energy which created micro-wormholes. (AUDIO: Situation Vacant)

The interior of wormholes, through which interstellar travel could be made, was called "worm space". (AUDIO: Nekromanteia)

Natural occurrences
There was a wormhole which connected Sentarion and Ruta III. It was closed by the Seventh Doctor in the 26th century. (PROSE: Shakedown)

The Wormhole of Calibri was located near Hazri. (COMIC: The Scarecrow)

In orbit of Agelaos was a wormhole that opened into the Time Vortex. (PROSE: The Weeping)

When told of the lie of the Timeless Child by, the Thirteenth Doctor received a vision of the child stood beneath a wormhole next to a monument on an unknown planet. (TV: Spyfall) She would later receive the same vision at the hands of Zellin, albeit this time she herself featured in the vision, watching the child from afar. (TV: Can You Hear Me?) Later the Master explained to the Doctor that these were repressed memories buried deep within all Time Lords, which stemmed from the Doctor's own history as the Timeless Child and the experiments performed on them by the First Tecteun in order to crack the regeneration code and give the Shobogans the ability to regenerate. (TV: The Timeless Children) Tecteun further clarified to the Doctor that the wormhole in question led to Universe Two, which she theorised to possibly be home to the Timeless Child's realm, although the Doctor was not so sure if that was the case. (TV: Survivors of the Flux)

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

The Daleks were capable of creating wormholes. (COMIC: Fire and Brimstone) They utilised a device known as a Oblivion Continuum, which drew power from a captured wormhole. Destruction of an Oblivion Continuum could destroy a planet. (TV: Victory of the Daleks)

Using Block Transfer Computations and wormhole technology, the Eleventh Doctor was able to connect the inside of the TARDIS and a safe Harry Houdini was locked inside. (PROSE: Houdini and The Space Cuckoos)

The Spillagers used wormholes to transport their fleets from their home dimension to other worlds. (AUDIO: Winter for the Adept)

Santa Claus used a temporal wormhole generator to send clones of himself through time in order to deliver presents to all children on Christmas Eve. (PROSE: The Man Who (Nearly) Killed Christmas)

The Stingrays travelled from planet to planet through wormholes they created. In 2009, they created a wormhole between San Helios and Earth, through which the 200 bus arrived. The wormhole was eventually closed by Professor Malcolm Taylor before most of the Stingrays could get through, thus saving the world. Knowing the Stingrays would just generate another wormhole, the Doctor planned to "nudge" them onto uninhabited planets so the Stingrays could consume everything without harming anyone, (TV: Planet of the Dead)

In 2010, Wanda Rothman's team found and accidentally activated a vodium sample. It started creating wormholes at a scientific conference, which pulled in several scientists. The Eighth Doctor and his friends were able to neutralise the vodium. (AUDIO: Situation Vacant)

In 2016, an artificial wormhole was run through San Francisco by the Celestial Hyperloop Corporation. The energy this leaked out caused several humans in the city to mutate in gargoyles. After Martha Jones had been partially transformed, Mickey Smith attempted to call the Tenth Doctor only to accidentally summon the Ninth Doctor. Together, the two managed to collapse the wormhole and save San Francisco. (COMIC: The Transformed)

The Shakri used wormholes to send transmissions to their Shakri cubes on Earth. There was also a wormhole portal in a lift in a London hospital that led to the Shakri ship. (TV: The Power of Three)

The Eleventh Doctor created a device which opened a wormhole to a pocket universe so he could go there and rescue Hila Tacorien. (TV: Hide)

In 2495, the Aranjia invaded Thelka using a wormhole. (COMIC: Blue Skies Thinking)

Phobos had a wormhole located on its surface. (AUDIO: Phobos)

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

Bianca's was accessed via wormholes which special taxis drove through. (AUDIO: The Wormery)

During the Last Great Time War, created a wormhole in his TARDIS to allow his counterpart to escape into the multiverse. (AUDIO: He Who Wins)

After flying off from Messaline, Jenny reconfigured her otherwise dead ship's force field generator into a wormhole generator. (COMIC: The Lost Dimension)

Behind the scenes
According to non-narrative information in DWBIT 37, the Hellmouth wormhole was believed to lead to the galaxy Nosfera II.