'''[[caption-width-right:350: The only one Iím really scared of is that VUG under the RUG.]]'''
* The Vug Under the Rug from ''There's a Wocket in my Pocket'' is considered by many to be his most frightening creature. Reason? [[NothingIsScarier We don't even know what it actually looks like.]]
** The Jertain in the curtain, another case of NothingIsScarier since all we see is the creature's feet.
** The Zall that runs up and down the hall is yet another.
** And the Quimney that runs up the chimney as well.
* The empty pants.
** Because while those empty pants are actually friendly and not only that but quite sensitive, there's a bit of NothingIsScarier in action because you never find out how they ''work''. They levitate along, walking above ground, have feelings, can see and hear without eyes and ears, and on the last page, they ''talk''.
* The vicious birds in ''Scrambled Eggs Super''.
* The Beasts from ''Oh Say Can You Say''
** as well as the Grox in the Grox Box if you spend your whole life seeing its hands as its bottom jaw... [[http://images4.wikia.nocookie.net/__cb20130512003257/seuss/images/thumb/d/d6/And_you_grox_must_be_packed_and_locked_up_in_a_grox_box.jpg/640px-And_you_grox_must_be_packed_and_locked_up_in_a_grox_box.jpg Try it.]]
** and the SHNACK IN THE SACK!!!
* Hop on Pop has the He that is after Me, the Night Fight, the Sad Dad and the hill that Will climbs that can all be kind of scary.
* The silhouettes in ''The Shape of Me and Other Stuff''.
* The Once-ler in the book of ''Literature/TheLorax'', though all we see are his hands (and occasionally, his eyes).
** From the same book, there's the fact that the forest creatures have to be sent away and are all negatively affected (the hummingfish can't hum, the swommee swans can't sing and the barbaloots are sick). Doubles as a TearJerker.
* Some people find the Zizzerzazzerzuzz from the ABC book scary, although [[NightmareRetardant it is a friendly creature]].
* ''Hunches in Bunches'' has the Four-Way Hunch, alongside the yellow super hunch.
* ''Oh The Places'' has two nightmare-fuelling illustrations; one for the streets you don't want to go down, and one for the times when you'll be alone and scared.
** Not to mention the green and black-striped creature that fills up two pages, even though it was petted by the boy.
* The [[MindScrew Paraphernalia Wagon]] from ''[[WesternAnimation/HalloweenIsGrinchNight Grinch Night]]''. [[http://www.youtube.com/watch?v=KeFaBvL72a8 Care to see?]]
* "Oh The Thinks You Can Think" has the Jibboo, who is depicted as a shadowy, bird-like figure walking toward a small boy in the street in the middle of the night. The caption somehow makes it worse.
--> What would you do if you met a Jibboo?
** In fact the Jibboo makes an appearance in the Paraphernalia Wagon cllip.
*** A significantly "high-octane nightmare fuel" version of the Jibboo no less. Makes me think Dr. Seuss knew the effect that that creature had on people.
* Trophy heads of Dr. Seuss creatures.
* The 5,000 Fingers of Dr. T, a film written by Dr. Seuss.
* The Wickersham Brothers, especially when accompanied by a [[VillainSong villain song]]. It gets worse when their uncles and cousins are introduced.
* The "Bitsy Big-Boy Boomeroo" from The Butter Battle Book. The book ''ends'' with the fear that one of them will drop it, which is [[LensmanArmsRace exactly the point]].
** The entire sequence that we see in the animated adaption has a MadScientist feel to it. It starts with red goo that comes to life and moves some controls around, and even features split-second glimpses of ghosts and snakes. The Chief Yookeroo's gravelly voice singing the accompanying song is also unsettling when combined with these eerie visuals.
* Foo-Foo the Snoo, a goat/satyr-like creature in a gimp suit with eyes [[TheFourthWallWillNotProtectYou glaring at the reader.]] [[http://seuss.wikia.com/wiki/File:Dr_Seuss_Foo_Foo_the_Snoo_I_Can_Read_With_My_Eyes_Shut.jpg Click if you dare ]]
* In One Fish Two Fish, the two children find a large aquatic creature with bright yellow eyes and curved teeth in a big glass jar in the park in the dark. They decide to take him home and name him [[CreepyGood Clark]]. Clark will live with them. Clark will grow and grow. Will their mother like this? They don't know.
** Technosagery's "[[http://archiveofourown.org/works/1627229 Out of the Dark]]" offers a take on what happened after Clark started growing.
* The Oobleck that kept everyone in Didd [[AndIMustScream rooted in one place]] and would have [[BuriedAlive buried them alive]] if the king hadn't made his apology.
* At the end of ''Thidwick the Big-Hearted Moose,'' the scene where Thidwick's [[http://photos1.blogger.com/blogger/5338/280/1600/seuss2a.jpg unwanted guests]] ended up being [[spoiler: stuffed and mounted when Thidwick threw his horns away]] is a bit disturbing.
* In ''The 500 Hats of Bartholomew Cubbins'' Bartholomew sentenced to have his head chopped off. He walks down to the dungeon and meets an executioner with an enormous ax. The magicians were pretty spooky too.
* The ending (or rather [[NoEnding lack thereof]]) of ''TheButterBattleBook'', with two sides of an [[SillyReasonForWar utterly pointless war]] [[MexicanStandoff standing face-to-face, ready to drop their respective world-destroying bombs]]. What makes this especially horrifying is that [[RealitySubtext it's a metaphor for the]] UsefulNotes/ColdWar.
* The lyrics to "You're a Mean One, [[Literature/HowTheGrinchStoleChristmas Mr.]] [[WesternAnimation/HowTheGrinchStoleChristmas Grinch]]" are a little disturbing if you think about them too hard, evoking some rather unpleasant imagery like "termites in your smile".