Trans-dimensional creatures that feed on realities damaged by temporal paradox, erasing people from existence so completely that nobody remembers they ever lived.
The Loom live outside normal space and time. They are drawn to timelines that have been broken by paradox and consume them, and they have been known to devour whole histories. In their presence time slows almost to a halt, so that only someone shielded against temporal effects can move freely.
When a Loom's tentacles fasten on a victim, that person is removed from existence, along with every memory of them. They are the main threat of the second season of Star Trek: Prodigy and are seen at their most dangerous in the two-part story The Devourer of All Things.
The young crew of the USS Protostar have caused a paradox by changing the events that created their own ship. Wesley Crusher, now a Traveler, guides them in repairing the timeline before the Loom finish feeding on it.