The Many-Angled Ones are fictional extradimensional beings linked to the Cthulhu Mythos.
They first appeared in Grant Morrison's story Zenith, which appeared in the British comics anthology 2000 AD. In Zenith they are known as the Lloigor, a direct reference to creatures from the Cthulhu Mythos. However, they appear somewhat different from the Cthulhu Mythos entities. In the comic, the many-angled ones have a dastardly plan to impose rigid geometrical order on the whole universe, essentially reducing it to clockwork.
The many-angled ones exist in a space with more dimensions than our own; hence, they appear to be many angled. As a result, when they manifest in our universe they appear as disconnected floating body parts of some larger beast that is complete in the higher dimension (similar to how a three dimensional being would appear in flatland as its parts pass through the plane of that two-dimensional world).
More recently, they have appeared in books by British authors or comics and video games from British comics writers who have worked for 2000 AD.
The many-angled ones were mentioned in Charles Stross's The Atrocity Archives. This work features the usual appearances by "nameless horrors of the abyss," which may or may not be many-angled ones. The many-angled ones are specifically stated as inhabiting Mandelbrot sets.
The beings were referenced in the DC comic book Hitman, by Garth Ennis, which briefly featured demons called "The Multi-Angled Ones" who end up killing most of Section 8.
They also appear in Simon R. Green's Secret History series of books The Man with the Golden Torc (2007), Daemons Are Forever (2008), and The Spy Who Haunted Me (2009).
In the Marvel Comics cosmic crossover event "Realm of Kings", written by Dan Abnett and Andy Lanning, Quasar travels through a time/space rift to an alternate earth with multiple Lovecraftian elements being part of the everyday reality of that world. There Quasar meets the Revengers, that world's counterparts to the Avengers, who received their powers from the Many-Angled Ones in exchange for the adoration of the heroes. That world's Iron Man states that the Many-Angled Ones have outgrown their reality and need a new place to feed and be worshiped. They intend for Quasar to show them the way to his Earth. The Many-Angled Ones are opposed on this Earth by the heroes who believe in pure science, such as the Vision. They later become the antagonists of The Thanos Imperative miniseries, and it is implied that Shuma-Gorath is one.
In the 2010 remake of the video game Splatterhouse, scripted by 2000 AD writer Gordon Rennie, the Mask of Terror refers to a group of Cosmic Horrors as the Many Angled Ones.