From the deepest layers of the Abyss to alien monsters from unknown realms and other worlds, this article lists the 15 scariest monsters in 5e D&D and explains what makes them terrifying!
The Most Scary Monsters in 5E D&D
1. Star Spawn Emissary
This alien monster from Van Richten’s Guide to Ravenloft is the worst enemy I can imagine facing. Contrary to other scary monsters in D&D 5e that are based on a creepy (cool) concept but don’t pack that much of a punch, a star spawn emissary is about as strong as any creature can get! When first encountered it assumes a shape-altering figure of a lesser star spawn emissary, a “bipedal mass of agitated organs, self-cannibalizing alien orifices, and appendages suggestive of forms it has previously assumed.”
This bad boy is a CR 19 creature and can deal psychic damage and stun a creature as a legendary action on every turn unless the target succeeds on a DC 21 Wisdom saving throw. Ouch. Combine this with 19 AC, 241 HP, and 3 legendary resistances, and most parties of adventurers will be in deep trouble. Well, the scary part hasn’t begun yet.
When a lesser star spawn emissary is killed, it turns into a greater star spawn emissary – a huge CR 21 creature with a staggering 4 legendary resistances, 290 HP, 15 AC, and some nasty ass abilities! For example, it can end every spell on creatures within 30 feet of it while also dealing an average of 32 psychic damage unless you succeed on a DC 23 Wisdom saving throw. Good luck with that. As if this 25-foot-tall pillar of flesh and voices of every form this monster has ever mimicked wasn’t nasty enough, the emissary can summon a Gibbering Mouther (a pretty frightening CR 2 creature) for every character who fails an insane Dexterity saving throw from its bile, taking 55 damage along the way) Did I mention that it has insane saves? Well, it likely won’t matter. Facing this extraterrestrial monster will be the final encounter for almost anyone. Count yourself lucky it can’t cast teleport!
2. Mind Flayer
The otherworldly mind flayer hasn’t become one of D&D’s most iconic villainous creatures without reason. At a glance, with just 71 hit points and a challenge rating of 7, the standard 5e mind flayer might look like an easy foe. That changes when you take a look at its abilities. Besides being able to cast dominate person, which is quite powerful for a CR 7 creature, the mind flayer has an extremely dangerous mind blast that damages and stuns everyone in a 60-foot cone who doesn’t succeed on a DC 15 intelligence saving throw. That may not sound too bad if you’re wizard, but for most classes in 5e, intelligence tends to be a dump stat which makes it a pretty hard save to succeed – and makes the mind flayer an extremely fearsome foe!
A mind flayer can also stun creatures by grappling them with its tentacles, and – when a target is incapacitated – it can deal 10d10 damage and extracts its brain if that damage kills it. Yes, that’s right. Bye-bye, brain. Combine this aberration with a few intellect devourers and even the bravest adventurers in the party will have nightmares about the encounter. If they escape with their brain intact, that is.
3. Oblex
Being the result of mind flayers experimenting on oozes should be enough to tell you how scary an oblex is. These extremely intelligent oozes are cunning hunters that feed on the thoughts and memories of their prey. As if a super-intelligent, memory-eating ooze wasn’t scary enough, an oblex is also able to create a physical impersonation of the creatures whose memory it has taken. These simulacrums are connected to its main body through a slimy tether, which is probably something your PCs are going to look out for on any creature they meet if they’re ever deceived by an oblex and manage to live to tell the tale. Like any ooze, an oblex can move through a space as narrow as 1 inch wide without squeezing, but unlike any of its slimy brethren, oblexes are clever enough to utilize their abilities in the most cunning and creepy ways imaginable.
The oblex is featured in Mordenkainen’s Tome of Foes and while think it’s one of the most gruesome monsters in D&D 5e, it has one of the most heartwarming origin stories as the young boy Nolan Whale came up with the concept when he worked with the D&D-team for a day as a part of a Make-A-Wish program! (Children are truly terrifying.)
4. An Ancient Dragon & an Evil DM
In a TTRPG that literally has dragons in its title, it feels wrong not having dragons at the top of the list of the scariest D&D monsters. Dragons are some of the most cunning and terrible foes you can meet, but in all honesty, I often don’t find facing them that scary. Though they have tons of hit points, high saving throws, and a nasty breath attack, their stat blocks are quite plain, and it’s up to the DM to roleplay dragons in a way that makes it as terrifying as they can possibly be. However.. while fighting a dragon that won’t flee its lair is one thing, facing off a flying dragon in a desert or while at sea with nowhere to escape is a whole other story. If the DM doesn’t mind having it fly off with one PC at a time before dropping them to their demise from 1.000 feet, or have the dragon only fly in and attack when its breath weapon is recharged, an ancient dragon in 5E becomes as fearsome as Smaug!
5. Sibriex
As ancient as the Abyss itself, these ugly demons are extremely dangerous and intelligent beings who’ve amassed information from across the planes for eons – according to Mordenkainen’s Tome of Foes they possess such knowledge that even demon lords seek their guidance.
Besides its awful appearance, what truly makes this super-intelligent demon scary is its ability to screw with the mind of its foes. A sibriex can cast feeblemind a staggering 3 times a day and can even cast spells as a legendary action (which means it can cast 4 spells in a single round). As an action, it can also force up to three creatures to succeed on a DC 20 Constitution saving throw or be poisoned and gain a level of exhaustion. This effect continues every round, until three successful saves have been made, or, of course, until the target reaches 6 levels of exhaustion and is transformed into a living abyssal wretch. What a dishonorable way to go for a hero.
6. Intellect Devourer
These nasty brains-on-legs bred by mind flayers hunt the minds of their prey – and are so creepy that they deserve their own spot on this list. An intellect devourer is a challenge rating 2 creature that can literally take over the body of a creature if it’s incapacitated. Like the mind flayer, they love brains, and if a character fails a DC 12 intelligence saving, an intellect devourer can roll 3d6 and reduce the intelligence of their prey to 0 if that amount exceeds the intelligence score of their target. Good luck with your 8 intelligence, martial classes!
7. Mimic
Mimics are shapeshifting monstrosities that come in all sorts of shapes and sizes.
While the “vanilla” challenge rating 2 mimic with 15 feet movement speed isn’t the strongest of creatures, having a treasure chest bite down on your arm as your reach for it, or being eaten by the chair you try to sit on after finally being able to take a short rest after a long day is something that will shock any adventurer (and make the players at the table triple check any object before touching it for the next few sessions!).
In the same alley of scary predators with deceiving appearances, we have a roper and a cloaker. The roper has a challenge rating of 5 and is indistinguishable from a cave formation while the much more intelligent challenge rating 8 cloaker can appear as a dark leather cloak.
8. Doppelganger
False appearances are scary, and in that category, nothing beats something taking over the identity and looks of another humanoid creature! Enters the doppelganger. These challenge rating 3 creatures are not terribly strong or exciting besides their ability to change into any small or medium humanoid (which can be done by several other creatures in D&D as well). 
What makes this ability much more troublesome on a doppelganger than on a deva, for example, is that taking over the identity of other creatures, living off their life, is simply how the doppelganger achieves its goals. These creepy creatures are described to follow or capture those they intend to impersonate. They might even keep someone they need to impersonate imprisoned as they use their innate ability to detect thoughts to extract the knowledge they need and display the appropriate mannerisms – and, of course, learn their desires and fears.
9. Beholder
There’s a reason this legendary flying eyeball with another ten tentacle eyes is featured on the front page of Monster’s Manual. Facing a creature with ten eyes is off-setting on its own, but when a single of those eyes can disintegrate you into fine dust, you know you’re in trouble. Of course, the eye rays’ effects are chosen at random, and not all of them are as powerful as the disintegration – but with six attacks on each round (including legendary actions).. well, you do the math!
The one thing talking against a beholder’s fearsomeness is its hit points – or rather, lack thereof. Its antimagic cone puts spellcasters at a huge disadvantage, but with a hover speed of just 20 ft., no abilities to escape, and no damage resistances, a smiting paladin or another martial class can make quick process of a beholder as long as it can get past its relatively high AC of 18.
10. Lich
A wizard hungry enough for power to transfer its soul to a phylactery – and clever enough to pull it off – is not someone you want to cross paths with.
These highly intelligent undead spellcasters don’t have a lot of hitpoints considering their challenge rating, but with power word kill, dominate monster, and all sorts of other amazing spells, that may not matter much. What makes the lich even scarier in my book is its rejuvenation ability. If you don’t find and destroy its phylactery, a killed lich will simply come back to life in a new body within 1d10 days – and a lich looking for revenge might be my worst nightmare!
11. Aboleth
An aboleth is an extremely dangerous (and intelligent!) aberration that lives mostly underwater. The aboleth has a nasty tentacle attack that curses its target so that it can only regain hit points underwater – and takes damage while outside of water. Since the curse can only be lifted by a heal or similar magic of 6th level or higher, that’s pretty scary. What truly makes the aboleth terrifying is its ability to enslave other creatures and to learn the greatest desire of any creature it communicates telepathically with. The only reason this creature isn’t higher on the list is that facing an underwater creature is not so scary while above ground.
12. Banshee
A banshee is the spiteful spirit of a female elf with a face wreathed in a wild tangle of hair and wispy rags fluttering and streaming around its body. While that’s scary in itself, it’s the wail of a banshee that makes it a horrific creature to encounter. While the wail “only” requires you to succeed on a DC 13 Constitution saving throw (which is actually fairly high for a creature of challenge rating 4), the effects are literally lethal as it instantly drops you to 0 hp!
13. Rust Monster
Almost as scary as being killed in D&D is losing your items. A rust monster is only measly CR ½, but if you hit this underground scavenger with a nonmagical weapon it starts to corrode! 
It can even corrode metal armor and cause you to lose the plate you’ve finally earned enough gold pieces to buy. It’s no joke that its descriptions read that “most dwarves would rather face a squad of orcs than confront a single rust monster”. Oozes are not as creepy to me (probably because I’ve encountered them so many times across many D&D adventures) but have the same corrosive effect and definitely deserve an honorable mention here.
14. Carrion Crawler
These large monstrosities are described as patient predators who might hunt a group of adventurers for hours during the night, following their light in the dark, before finally setting up an ambush. It then uses a nasty poison to paralyze its target and quickly escapes out of reach by climbing to a ledge high above the ground or an isolated pathway. Luckily, they’re just CR 2 creatures, and you get to roll a save each turn to get out of the paralysis. Just the thought of it, however…
15. Tarrasque
The king of the Monster Manual, the almighty Tarasque, obviously deserves a spot on the list. Even though this all-eating monster might not be the scariest in classic horror terms, it just doesn’t get much scarier than facing off a tarrasque when it comes to raw strength. While its insane challenge rating of 30 is well-deserved, a tarrasque is still relatively easy to outwit and escape from, and that’s why it’s not higher placed higher up on this list of scariest monsters.
Conclusion
That concludes our picks for the scariest monsters in D&D 5e. As you can see, some of the common themes that make a monster scary in my book are intelligence, nasty abilities that can completely take a character out of combat, turn them against their friends, or even cause permanent damage to their mind and soul, or equipment. If a creature can control your mind, that’s just a lot scarier than a hard-hitting giant to me!
Another prevalent theme on this list is otherworldliness. Creatures like mind flayers, oblexes, star spawn emissaries, and sibliexes are all examples of creatures that are driven by motivations that our common brains almost can’t comprehend – and not just because we’ve faced an intellect devourer!
Our newest book Milando’s Guide to Magical Marvels brings more than 150 pages of magical content to your table – including a whole bunch of terrifying monsters!
Those of you who’ve seen Netflix’ Stranger Things will probably agree that what makes the “Demogorgon” of the show truly terrifying is what we do not know about it! Fighting something you don’t quite understand is just extremely unsettling.
Even more so than for ordinary encounters, this is the case when talking about the villain of a campaign. Take the legendary vampire lord of Barovia in the official campaign Curse of Strahd, Strahd von Zarovich, for example. What makes him a terrifying entity is his ominous presence, immense knowledge, and ability to break some of the rules that confine ordinary vampires.
Or, if we take the portrayal of Demogorgon in the campaign book Out of Abyss, what makes the Prince of Demons frightening shouldn’t be its stats (though any CR 26 is scary!) but that the characters on one hand have a very limited understanding of this vile, unnatural creature, and on the other hand witness the extreme havoc it wreaks after it has found its way to the Underdark from the Abyss!
The scary part, for me at least, is going up against something that you know to be extremely dangerous without quite understanding it (and thus the abilities it may or may not have) at the same time!
Anyway, that’s our list for the top 15 scariest monsters in D&D 5E. Let us know in the comments if you agree with our picks – or share your own list of the monsters your fear the most!
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S. K. Valeur