The Loom were a trans-dimensional species that fed on inhabitants of dimensions suffering from temporal paradoxes. They had been known to devour entire timelines. The Loom only appeared if tears in the fabric of reality were to remain opened for too long.
The Loom could also slow time to a crawl, making it impossible for people to escape them unless they had some form of protection against time anomalies. Phasers were largely ineffective against them unless matched to their phase variance.
The Loom could be fooled by holograms or mental projections.
Zero could sense that the Loom were possessed of an insatiable hunger. (PRO: "Ouroboros, Part II")
When they attached their tentacles to an individual, that being was erased from existence – all memories of them as well any digital records were lost as if they never existed. Only those who wore phase discriminators and temporal stabilizers, or witnessed the incident would remember the individual that was erased. (PRO: "The Devourer of All Things, Part II")
History
The first encounter with a Loom was the USS Voyager-A in search of Gwyndala, unaware that a hologram had taken her place, much to its anger when it tried to erase her. The event caused Voyager's logs to lose eight minutes. The crew were later able to isolate the sound of the Loom's chittering.(PRO: "The Fast and the Curious", "The Devourer of All Things, Part I")
When Dal R'El, Gwyndala, Rok-Tahk, Jankom Pog, Zero and Murf meet Wesley Crusher, he warned them of the existence of the Loom, who were invading the prime universe as a result of the paradox they created as a result of the USS Protostar failing to arrive on Tars Lamora. The Loom soon invade the time ziggurat, slowing time around everyone save for Gwyn and Wesley, who were wearing temporal stabilizers. Encountering one Loom, Wesley is able to fool it with a mental projection of Gwyn, before returning to their allies to equip them with more temporal stabilizers, before taking cover in the Traveler's vault.(PRO: "The Devourer of All Things, Part I")
Voyager soon arrived at the Traveler's planet and beamed down an away team composed of Commander Tysess, Ensign Middleton and Cadet Maj'el, who soon encountered the Loom. Middleton became an unfortunate victim of the Loom and was erased, with only Tysess recalling he existed upon being beamed back to Voyager. The Loom soon corner Maj'el, who chose to remain, in the time vault, forcing Dal to allow her entry into their hideout, only to expose their location to the Loom. The Loom proceeded erase the Infinity before cornering the group outside the ziggurat, only to be fired upon by Voyager, prompting the Loom to change their target. The Loom then easily penetrate Voyager's shields, erasing several crewmembers, before Vice Admiral Kathryn Janeway got into a shuttlecraft and matched its weapons to the Loom's phase variance, luring them all away from Voyager, managing to kill one after firing a spread of quantum torpedoes. The Loom then resume their attack on the ziggurat, but Wesley sends the seven cadets to the Protostar's location as well as Janeway back to Voyager, before creating an explosion using space-time-thought in combination with the Boreth Crystals and the Orb of Time, causing the planet and the Loom to vanish.(PRO: "The Devourer of All Things, Part II")
The Loom invade the mirror universe as a result of the Protostar creating an interphasic rift from proto-warping that weakened the fabric of reality that caused Voyager to become splintered in different realities and began attacking the ISS Voyager. Though they slowed time, Gwyn was able to activate the deflector dish to emit an inverse tachyon pulse to repair the fissure, returning everyone to their proper dimension.(PRO: "Cracked Mirror")
Asencia managed to capture a Loom at her prison in the Wastes of Solum and used it as a method of execution. This Loom was forced to chase Dal's group after they were captured, but Admiral Janeway managed to breach the prison by using her combadge as a makeshift bomb, which resulted in the Loom's collar coming off, allowing it to go free, erasing several Vau N'Akat soldiers in the process. It nearly erased Asencia but then retreated for unknown reasons.(PRO: "Touch of Grey")
During the Battle of Solum, the Loom invade the prime universe through the stable temporal wormhole that was created in swarms, intent on wiping out everything starting with Solum. Voyager is able to escort the Protostar past the Loom, sending the ship back to Tars Lamora, fixing the broken timeline, causing the Loom to cease their attack and depart the prime universe.(PRO: "Ouroboros, Part I", "Ouroboros, Part II")
Appendices
Appearances
Background information
The Loom conceptually resemble the Reapers from Doctor Who. Both creatures were attracted by temporal paradoxes to remove the offending element.