List of The Phantom Tollbooth characters

• Milo, a school-aged boy, the main character, bored with life prior to receiving the gifts. He was a very confused boy. Milo's age is not stated. In early drafts, Juster put Milo's age at eight, then nine, before concluding that it was "not only unnecessary to be that precise but probably more prudent not to do so, lest some readers decide they were too old to care..."[1] A very early draft has in his place a ten-year-old named Tony with his parents Mr. & Mrs. Flanders.[2]
• Tock, a "watchdog" (with an alarm-clock in his body) who befriends Milo after saving him from the Doldrums. Tock was based on one of Juster's favorite characters, Jim Fairfield from Jack Armstrong, the All-American Boy.[3]
• The Humbug, a pompous insect who joins Milo and Tock on their quest. Juster said, "For the sake of balance, I wanted someone who was the reverse [of Tock]— a bad influence, someone who is a braggart, not very honest, a huckster, not too trustworthy, a self promoter—in short, someone sure to steer Milo wrong."[4]
• Rhyme and Reason, two princesses who settled disputes. The kings banished them to the Castle in the Air, thus being Milo's MacGuffin. They explain to Milo the reason why he has to study things. Both Feiffer and Juster were dissatisfied with the portrayals of Rhyme and Reason, Feiffer thought they looked too much like beauty pageant girls, and Juster thought they were "too much like the girls in my classes in elementary school — well behaved, responsible, orderly, a force for good, but a damper on the chaos I thrived on as a child."[5]

• King Azaz the Unabridged, the King of Dictionopolis, one of the two rulers of Wisdom.
• The Mathemagician, Azaz's brother and the other ruler of Wisdom. He rules the city of Digitopolis.
• Faintly Macabre (or Aunt Faintly), the Not-So-Wicked Which. When she regulated all words used in public, she became so stingy with them that people became afraid to talk at all. She tells Milo that she can be released from the dungeon with the return of Rhyme and Reason. (She isn't seen at the end of the book, so whether she was released or not is never resolved.) Juster's comment that "witches hate loud noises" was only a plot device that he made up.[6]
• Chroma, conductor of an orchestra that plays all the world's colors. Feiffer's drawing of Chroma was loosely modelled on Arturo Toscanini[7]
• Dr. Kakofonous A. Dischord, a scientist who enjoys creating unpleasant sounds, and curing pleasant sounds. Feiffer's illustration of him bears a striking resemblance to Groucho Marx as Dr. Hugo Z. Hackenbush.[8]
• The Awful DYNNE ("awful din"), a genie who collects noises for Dr. Dischord.
• The Soundkeeper, who loves silence, rules the Valley of Sound. Her vaults keep all the sounds ever made in history.
• The Dodecahedron, an inhabitant of Digitopolis with twelve faces, each of which shows a different emotion. Originally, Juster had J. Remington Rhomboid as the Mathemagician's assistant[9] a two-dimensional character with no depth, who would have become three-dimensional as a reward[10]
• Officer Short Shrift, a very short man, the police force of Dictionopolis.
• The Lethargians, lethargically small, mischievous creatures who live in the Doldrums and are irresponsibly lazy.
• The Spelling Bee, an expert speller, but sometimes an enemy of the Humbug.
• .58, a boy who is only .58 of a person from an "average" family, which has 2.58 children.
• Canby (can be), a frequent visitor to the Island of Conclusions, who is as much "as can be" of any possible quality. Play on the words "can be".
• King Azaz's advisors: the Duke of Definition, Minister of Meaning, Count of Connotation, Earl of Essence, and Undersecretary of Understanding, all of which have the same (or almost the same) meaning. They welcome Milo and Tock to Dictionopolis as soon as they enter.
• The Whether Man, who deals with whether there will be weather, rather than the specific nature of the weather. Note that Feiffer drew Juster as the Whether Man.[11]
• Alec Bings, a boy of Milo's age and weight who sees through things. He grows downwards from a fixed point in the air until he reaches the ground, unlike Milo, who grows upwards from the ground.
• The Everpresent Wordsnatcher, a dirty bird that "takes the words right out of your mouth". He is not a demon per se, as everyone who meets him just sees him as an annoyance. Juster considered naming him the "red crested word snatcher".[12]
• The Terrible Trivium, a demon in the Mountains of Ignorance who wastes time with useless - or "trivial" - jobs. Leonard Marcus observes that The Phantom Tollbooth itself was a procrastinatory diversion and that it's fitting that this occupies the place of pride as the first demon in the rogues' gallery of demons.[13]
• The Demon of Insincerity, a misleading demon who never says what he means.
• The Gelatinous Giant, a demon who blends in with his surroundings and is afraid of everything, mostly ideas.
• The Triple Demons of Compromise, one short and fat, one tall and thin, and one exactly like the other two. Norton gave these a cameo role just to describe something impossible to draw for Jules Feiffer.[11] These were, in notes, originally the Twin Demons of Compromise[14]
• The Senses Taker ("census taker"), a demon who robs Milo, the Humbug, and Tock of their senses by wasting their time and asking useless questions. Feiffer's illustration was an experiment using spattered ink, later used by Gerald Scarfe and Ralph Steadman a few years later.[15]

In Juster's notes and drafts, there are a number of characters for which Juster had sketched, but did not use in the final drafts: Milo:A boy who was unused due to technical failures.

• The doorman, who received the package of the tollbooth[2]

• The small, wild-eyed little man who kept breathlessly repeating "It's here, it's here" who in early drafts, brought the tollbooth package to the doorman.[2] In the final draft, it is not known who brought the tollbooth, or who sent the tollbooth.
• Mr. and Mrs. Flanders, the parents of Tony (the protagonist's name in early drafts).[2] Tony later became Milo, the latter's age and last name never said. Milo's parents do not appear.
• The Chocolate Moose, who is always afraid he is not light enough[16]
• The Star Gazer, who wonders about everything[16]
• The Seal of Approval[16] which was to be one of the princesses' pets.[9]
• The Social Lion[16] Another which was to be one of the princesses' pets,[9] with a pun about "reading between the lions".[17]
• The Inventor, who never leaves well enough alone and invents improvements or things that have no use e.g. straight bananas and square oranges for easy packing in a spherical car, etc.[18]
• The Hitch-Hiker who always leads Milo into doing things the easy way and jumping to conclusions[18]
• The Optometrist, who fits the rose colored glasses[18]
• The Facsimile, who can be just like everyone else[18]
• Peter Paradox, an assistant to the Mathemagician[9]
• The Adding Machine, a robot assistant to the Mathemagician[9]
• The Lucky Boy, a boy that always gets lucky.