Angels are one of the most easily recognized symbols of Judeo-Christianity in the world. Servants of God these figures are found all throughout the Torah, the Bible, and the Koran respectively, but even those who don't consider themselves religious still recognize angels if they saw them.
Or would they?
Angels have become such a large part of common culture that most people forget how they're described in the source material. Far from the tall, broad-shouldered beings with golden hair and white fluffy wings we typically think of, angels were traditionally alien beings of horrific, mind-bending appearance. It's why their first words to anyone who saw them were typically, "Be Not Afraid."
Also, have you ever wondered what the real difference between demons and devils is?
Just How Strange Do Angels Really Look?
Angels, being servants of the divine, are gifted with a lot of power. One of the main uses of that power we see is either the ability for angels to move invisibly, or to appear as common men so they can walk unnoticed among the population.
But what do angels look like when they're not just trying to blend in with the Lord's blander creations? Well it depends on the angel in question.
Seraphim are a good example. Fairly high up on the divine corporate ladder, the name seraphim means either, "the burning ones," or "the ones of love." I'm sure you see how those two definitions could get confused. Seraphim have six wings, but four of them are used to cover their bodies while only two are used to fly. That's so people who see them won't burst into flames or go blind upon witnessing the burning perfection of the seraphim's actual form. It's similar to the story of Eros's lover, who opened her eyes and was blown to dust at the sight of his divine beauty. Not exactly the sort of creature you want hovering over you to deliver a message in the fields.
Another example are cherubim, more commonly referred to as cherubs. These creatures are usually depicted as cute little pudgy angels with bows and arrows, and they're popular Hallmark heralds for Valentine's Day. They're often mistaken for Cupid is what I'm saying. According to the Bible though, cherubs are actually creatures with four faces (one on each side of their heads), and with four wings. Arranged in a square these angels can travel in any direction without turning. These are the heaven's heavy hitters, and the cherubs guard the kingdom of heaven.
As a last example there are also throne angels (which are sometimes transposed with the cherubim, depending on the chapter and verse... it's not clear who has what jurisdiction in heaven). These creatures look like wheels within wheels (sort of like a gyroscope) which have eyes that can see in all directions around the rims. And as if that wasn't bizarre enough they float with no wings, and are constantly burning. Hence the phrase wheels of fire.
Why Didn't I Know That?
There are a lot of reasons, but the biggest is pop culture. Angels are popular fodder and they've been used by everyone from John Milton to the person I shall not name responsible for the film Legion. Because angels in pop culture are very human in appearance the description of beings that sounds more like H.P. Lovecraft than the Old Testament has sort of fallen by the wayside. It's simply not the popular image people share, and it would often be harder to correct that image than it would be to just allow it to remain the default perception people share about these divine servants.
Of course once you know the truth you can't simply un-know it.