Rift (Whoniverse)

The Cardiff Rift is a fictional wormhole in the science fiction television series Doctor Who and Torchwood, one end of which is located in Cardiff Bay, Wales. The other end is apparently floating freely through spacetime, and matter and radiation can pass through the Rift, allowing extraterrestrial and extratemporal artifacts, and occasionally life-forms, to "wash up" in Cardiff. It is described as "Unpredictable and elusive, it’s a gateway for alien creatures, alien weapons, all manner of alien technology and time anomalies to enter our world" and the "flotsam and jetsam of the universe since the dawn of time."

The Rift has been featured in episodes of Doctor Who and is central to the spin-off series Torchwood, which concerns a branch of the Torchwood Institute created to monitor activity around the Rift. The Rift acts as a plot generator, providing a wide and potentially unlimited array of possible plots for the series, much like the Hellmouth in Buffy the Vampire Slayer and the Bajoran wormhole in Star Trek: Deep Space Nine.

The Rift first appears in the Doctor Who episode "The Unquiet Dead". This episode takes place in 1869, when the Gelth, gaseous humanoid organisms, pass through the Rift into a funeral parlour, where they are able to 'possess' the corpses. It is established that the Rift releases radiation, prolonged exposure to which can grant psychic powers to people, including Gwyneth, a servant in the parlour. The Doctor speaks with the Gelth via Gwyneth in a séance, where they claim to be few in number following the Time War, and ask for the Rift to be widened, allowing the remaining Gelth to live in the corpses. However, after the Doctor discovers that the Gelth are in fact far more populous than first claimed, and intend to slaughter the human race to provide themselves with inhabitable corpses, Gwyneth sacrifices herself by causing a gas explosion, which seals the Rift and apparently kills the Gelth.

...
Wikipedia