Eldritch abominations are entities that are so bafflingly terrifying that they're nearly impossible for humans to comprehend. Think a giant tentacle monster with hundreds of eyes that comes from another dimension and you're on the right track. While eldritch abominations in anime are usually comprehensible due to anime's visual nature, these creatures can still get pretty horrifying.
Some, like Lily Carnation of One Piece, are monstrous beasts that devour human flesh. Others, like the Nightwalker from Princess Mononoke. are more ethereal but are no less destructive. Whether they're beautiful, terrible, or something in between, these Eldritch abominations will make your hair stand on end. Which ones do you find the most unsettling?
Pride is a homunculus, a fact which already puts him in the running for Eldritch Abomination. So, why Pride as opposed to one of his siblings? Because he also looks the part. When he isn't in the guise of a cute little boy, he's a teeming mass of shadows covered in eyeballs. These aren't just terrifying to behold, they're also nearly invulnerable weapons.
The Godhand is a group of five demon lords whose powers are beyond comprehension. Each one of them was once a human who possessed a Crimson Beherit - an artifact that allows the owner to shed their physical form and attain ultimate power in a bloody event called the Eclipse, which occurs every 216 years.
For the most part, the Godhand doesn't take physical form - instead, they possess various objects and beings in order to interact with the physical world. They are capable of manipulating the threads of reality, and destroying just about everything they encounter.
The Elder Bairns are a group of ancient monsters who are possessed by a seemingly endless desire to feed on human flesh. Though some of them are able to speak human languages, they still can't really be reasoned with, as they see humans as nothing more than livestock. The Bairns can take a variety of forms, ranging from flowers and rabbits to shadows and giant eyeballs - but no matter what form they take, they're always horrifying.
The Angels in Evagelion are a lot of things, and we won't get into all of them here - but the quick and dirty definition is that they're the children of Adam, the original seed of life on Earth before Lilith showed up and created humans. NERV's job is to fight these Angels in order to protect humanity - though it goes a lot deeper and gets a lot creepier than that. The Angels themselves can look like anything from a human being to a giant floating sphere. They're difficult, if not impossible to comprehend - and the same can be said about Adam and Lilith.