Lovecraftian Horrors

"It was a terrible, indescribable thing vaster than any subway train—a shapeless congeries of protoplasmic bubbles, faintly self-luminous, and with myriads of temporary eyes forming and un-forming as pustules of greenish light all over the tunnel-filling front that bore down upon us, crushing the frantic penguins and slithering over the glistening floor that it and its kind had swept so evilly free of all litter."

- A description of Shoggoth.

The term "Lovecraftian Horrors", also known as Eldritch Abominations or Cosmic Horrors, applies to villains, objects, places, or even events that are or eventually transform into otherworldly entities or objects beyond rationalization, too alien from "normal" flesh-and-blood beings to be described properly, and most often madness-inducing. Alternatively, beings whose aspect is clearly stated to be an approximation of what they really are, something that humans can process while their real form is unconceivable. At the very least they must be as close as possible to such beings and a clear, stated tribute to Lovecraft.

History
Howard Phillips Lovecraft was a horror writer who influenced the genre greatly. Instead of traditional villains, he created "horrors": indescribable, indefinable, inconceivable beings, whose existence contradicts the laws of physics, whose aspect alone is beyond human logic, and as such can induce madness by their mere presence. Although malevolent by human standards, most of Lovecraft's "horrors" are amoral beings that are either insane or too alien for humans to understand. Very few of them are desirable to be around, however, and thus are similar to villains in the sense of being harmful, and generally a threat to the world at large.

Religion

 * The Devil/Satan (who is often called the King or Prince of Darkness) (Judaism and Christianity)

Literature

 * Cthulhu (H.P. Lovecraft)
 * Pennywise (It)
 * The Nothing (The Neverending Story)

Films

 * Gozer (Ghostbusters)
 * Deadites (Evil Dead franchise)
 * Death (Final Destination franchise)
 * The Nightmare King (Little Nemo: Adventures in Slumberland)
 * Labby (Where the Dead Go to Die)

Internet

 * Zalgo
 * Slender Man
 * Smile Dog
 * SCP-106

Comics

 * Red Lantern Corps (DC Comics)
 * Dormammu (Marvel)

Television

 * The Darkness (Supernatural)
 * The God of Darkness (RWBY)
 * The Monster (Stranger Things)
 * Gunter (Adventure Time)
 * House (Doctor Who)

Video Games

 * Flowey (Undertale)
 * God (Silent Hill)
 * Gravemind (Halo franchise)
 * Dormin (Shadow of the Colossus)
 * Black Beast (BlazBlue)
 * The Queen of Hearts (American McGee's Alice)

Anime and Manga

 * Kyuubey (Puella Magi Madoka Magica)
 * Buu (Dragon Ball franchise)
 * Alucard (Hellsing franchise)
 * Chaos (Sailor Moon)

Gallery
NOTE: The limit is for 20 pictures only