* 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 Red Under the Bed, which was scrapped for being too scary.
** 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.
* 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 and the Sad Dad that can all be kind of scary.
* The Once-ler in the book of ''Literature/TheLorax'', though all we see are his hands (and occasionally, his eyes).
* Some people find the Zizzerzazzerzuzz from the ABC book scary, although it is a friendly creature.
* ''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.
* 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.
* 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]].
* 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.
* 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.