This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / Norse Mythology
Ragnarök is really the Nightmare Fuel-version of Hilarious in Hindsight. First considering Hati: a wolf big enough to eat the moon. He must be larger than the earth and have his own gravity field. Then consider the environmental effects of the moon being eaten. Then Jörmungadr, he encircles the whole god damned earth! His head must be larger than Great Brittan! It said that when he writhes it causes tidal waves. Considering his size those are freaking 2012 sized waves. Then Fenrir. He eats the freaking SUN! How larger is he really? Considering the sun is more than a hundred times bigger than earth, Fenrir is even bigger. And Níðhöggr is still supposed to be larger than Fenrir. And when Fenrir eats the sun, half of the world would see him do it, then 8 minutes later the sky would go black forever and the Earth would likely be thrown out into deep space along with the rest of the solar system unless it would all be drgged into Fenrir. Fimbulwinter indeed. Granted, the Norsemen knew little about gravity or how big the sun and the moon really was, but this is not the point of this trope is it?
Neil Gaiman's 2017 rendition dials it up, predictably by making one small addition. Unlike other versions which present the Norse Myth as already having happened, Gaiman treats the mythology as living and active. Ragnarok hasn't already happened, it will happen sometime in the future...i.e. our future. The Norse Gods are presented as our gods. The beginning of Ragnarok is when Jormungandr the Midgard Serpent rises to the surface, and his black venom spews out killing all ocean life, a reference to the deepwater horizon spill, the oceans boil and climate changes.
Náströnd (The Bay of Corpses). This is where Níðhöggr lives and the evil doers are sent according to the Norse myths. From the roof of the hall hangs serpents who drops venom and there are rivers running with venom, it's cold and there is no light. And Níðhöggr sucks corpses. This is where the evilest people are sent, wolfish murderers (killers of the defenseless), the ones who seduces anotherís close-trusted wife and those who give false oaths and perjure.
The binding of Loki.
To iterate; Loki is chained to a rock with venom constantly dripping onto his face and into his eyes. This is so painful that his spasms are what causes earthquakes. Fortunately, his wife, Sigyn, is there to alleviate the pain by holding a bowl over his head to catch the poison. Unfortunately the bowl has to be emptied when it gets too full, lest the poison starts overflowing, and this causes the poison to drip into his eyes once again. For added fuel, his escape from this Fate Worse Than Death is what jumpstarts Ragnarök
The Valkyries. Read Darraðarljóð (The Song of Darts) and you get the point.
The warp is made of human entrails; Human heads are used as heddle-weights; The heddle rods are blood-wet spears; The shafts are iron-bound and arrows are the shuttles. With swords, we will weave this web of battle.
The myth of Sleipnir becomes A LOT less funny when you realize that Loki was more or less RAPED by a horse...and as someone who has a grandparent who had horses and got an up-close look...a horse's ding dong is NOTHING to sneer at, mare form or not.