Milo
Milo is a young boy and the main character in the novel. At the beginning of the book, he is a morose child who is constantly bored despite owning many toys and books. He is not really interested in anything - in fact he is positively uninterested in everything and cannot see the point to most of the things he is required to study in school. He is never happy where he is and is always looking to be somewhere else. All of these qualities make him the perfect candidate to be changed for the better by the phantom tollbooth.
Despite having no real passions or interests, Milo is an intelligent child with a good head on his shoulders. This becomes evident as he travels through strange lands where he is required to think a great deal and is challenged by new words, strange concepts, and mathematical problems. He is also required to have an open, courageous, and strategic mind, which he manages to do. He is a likeable boy who remembers the manners he has been taught. At the end of the book, he is forever changed by his adventure and constantly in awe of all the amazing things around him and the fact that he has so much to do, read, and learn about.
Tock the Watchdog
Tock is a watchdog who makes a tick noise. His brother, Tick, makes a tock noise. This is the cause of tremendous trauma in his family. Tock is a true and loyal friend to Milo and accompanies him on the entire journey to rescue the princesses and bring them back to Dictionopolis. His main preoccupation is time; chiefly, respect for it and abhorrence of wasting it. He is very precise and very helpful whenever a logic problem or mathematical challenge presents itself. He has a great deal of courage and is always ready to support Milo.
The Humbug
The Humbug is Milo's other traveling companion. Despite all efforts to the contrary, he is also courageous and puts himself in considerable physical danger by offering himself as a ladder for the others to climb up out of the abyss. He has lamentable mathematical abilities and answers "seventeen" to every question, but believes himself to be a good problem solver and cannot understand how he has yet again managed to come up with the wrong answer.
Princesses Rhyme and Reason
The lovely Princess Rhyme and Princess Reason are stable, logical, and reasonable. They are the arbiters of calm in the kingdom; however their refusal to come down on anybody's side about whether words or numbers are more important results in their banishment. It is not until their rescue and return that harmony is restored again.
King Azaz the Unabridged
King Azaz rules Dictionolpolis and reveres words. He delights in their appearance, sound, usage, and collection. He gathers courtiers around him who are verbose and full of prose. He is the person who charges Milo with the task of rescuing the princesses and bringing them back to the kingdom so that there can be peace between the kingdoms of Dictionopolis and Digitopolis.
The Mathemagician
The Mathemagician rules the kingdom of Digitopolis. He believes numbers are superior to words and loves everything about them. He challenges Milo to come up with the answer to many mathematical problems, including the identity of the biggest number in the world. He is rather unhappy about the divide between the kingdoms, but blames King Azaz and on principle disagrees with everything he says or believes.
Alec Bings
Alec is a boy whom Milo meets on the outskirts of Dictionopolis and who like everyone in his family is born floating in the air and grows downward until his feet reaches the ground. He consequently looks at things from an adult perspective from a very early age. He is also adamant that everyone has their own point of view, which of course is much easier when one is floating above everyone else like Alec is.
Chroma the Great
Chroma conducts all of the colors in the world with an enormous symphony orchestra whose combined playing makes everything in the world the correct color. Although Milo thinks this might be easy, it transpires that it is exceedingly difficult and only Chroma knows how to conduct the symphony so that the perfect allocation of colors is achieved.
The Dodecahedron
The Dodecahedron is both introduction committee and guide for Milo when he reaches Digitopolis and also makes sure that nobody steals any numbers from the numbers mine. The Dodecahedron is a shape with twelve faces and he also wears a different expression on each face to save time and effort in altering them. He introduces Milo to the Mathemagician and is very good at explaining numerical concepts to the boy.
The Whether Man
The Whether Man is the first person whom Milo meets. He welcomes Milo to the Land of Expectations and encourages him to begin his journey.
The Lethargians
These grayish, homogeneous creatures live in the Doldrums and are excessively lazy and prone to procrastination. They inform Milo that one cannot laugh or think in the Doldrums.
The Spelling Bee
A massive bee who spells words throughout his utterances. He does not care for the Humbug and the two get in a rough-and-tumble fight.
Officer Shrift
A two-foot-tall police officer who is the only law enforcement in Dictionopolis. He is loud and rigid and blustering; he acts as judge and jailer as well, and arrests, sentences, and jails Milo and Tock.
Faintly Macabre
The which (not witch) whom Milo and Tock meet in jail, Faintly Macabre is the king's great-aunt. She was once in charge of all the words in Dictionopolis, but became miserly with the words and was thrown in jail. She tells them the story of Rhyme and Reason, thus helping them begin their quest.
Kakofonous A. Dischord
The Doctor of Dissonance, Dischord lives in a carnival wagon where he creates loud and wild sounds in his laboratory. He rescued DYNNE and made him his assistant. He delights in noise and wishes to cure the world of beautiful signs.
DYNNE
He is a smoky, amorphous creature who acts as assistant to Dischord. He is emotional and dramatic.
The Soundkeeper
She is an old woman who was guardian of all sounds past and present, but then ruled that silence must reign in the Valley because people were using sounds poorly and preferred terrible sounds. She gives Milo a tour of her fortress and explains how sounds are made and archived. When Milo releases all the sounds, she is initially upset, but learns to be more open to how sounds are used.
Canby
He is a man who lives on the Island of Conclusions and explains how he "can be" this or that - fat, thin, happy, sad, etc.
.58
A friendly child who lives along the staircase to Infinity, he is the .58 of families' 2.58 average of children. This means he looks otherwise normal but only has .58 of a body. He tells Milo how valuable averages are.
Everpresent Wordsnatcher
A dirty and rude bird the travelers encounter on the journey in the Mountains of Ignorance, he constantly interrupts them. He tells them he was from a place called Context, but rarely goes there anymore. He is not a demon but rather a nuisance.
Terrible Trivium
He is an elegant but malicious man with a blank face whom Milo and friends meet in the Mountains of Ignorance. He gives them useless and petty tasks to waste their time and effort. He tries to beguile them into staying but the demon of insecurity leads them away.
The Demon of Insecurity
While he pretends to be a large, ugly creature, he is actually small and furry. He is very emotional and says he does not know what he does or who he is. He leads Milo and friends away from Terrible Trivium into a ditch.
The Gelatinous Giant
He is a formless creature who takes the shapes of things he is near - in this case, a mountain. He almost eats Milo and friends, but releases them when he hears that Milo has a box of ideas.
Senses Taker
He is a little man with thick eyeglasses who takes the information of travelers seeking to enter the Castle in the Air. He is fastidious and detailed. He helps people find what they are not looking for, hear what they are not listening for, and steals their senses of purpose and duty; he cannot take their sense of humor, though.
