|Born||Sometime between 1949 to 1950|
|Primary wardrobe||Yellow shirt|
|Motion capture|| Eddie Deezen (primary)|
Jimmy "Jax" Pinchak (additional)
Know-It-All is one of the children that rode on the Polar Express. At first, he seems smart, but it is soon apparent that he only wants to be smart and needs the ability to learn more. At some point, hero girl mutters, "Dillan," while referring to know-it-all, possibly calling him by his first name.
Hero Boy first meets Know-It-All on the train right after he gets on and takes a seat. Know-It-All asks Hero Boy if he knows what kind of train he is on. Hero Girl joins in the conversation and answers the question by simply saying it is a magic train that goes to the North Pole. Know-It-All then goes on to give some detailed information about the train before noticing Herpolsheimer's with a Christmas display outside and calls out to the other The Christmas display has presents, to which Know-It-All exclaims, "I want all of them!"
The Conductor punches the letters "LE" out of the ticket of Know-It-All, who views the Conductor as a show-off and wonders what the two letters mean. Hero Girl would later the same letters. Know-It-All is also surprised to notice train stopping at Billy's house, thinking Hero Boy was supposed to be the last one. Billy turns the trip down, but changes his mind and runs after the train as it leaves, but has difficulty getting on, so Know-It-All suggests that Hero Boy pulls the emergency brake, which he does, stopping the train and allowing Billy to get on board. Suddenly, an angry Conductor storms in and Know-It-All tells Hero Boy on him, despite it being his suggestion.
When Hero Girl goes to give Billy some hot chocolate, Know-It-All tries to persuade her out of it, noting that "it's a violation of railroad safety regulations for a kid to cross moving cars without a grown-up," before the Conductor shows up to assist her. He does it again to Hero Boy when he leaves to give Hero Girl her ticket back. Soon, the Conductor comes to punch Hero Girl's ticket, but she cannot find it, so he takes her to the back of the train. Know-It-All thinks she might get thrown off the train and points out that they might slow down for her, but not come to a complete stop, giving Hero Boy the idea to pull the emergency brake again until he finds the ticket stuck in the air vent, grabs it and goes after Hero Girl and the Conductor.
After the train passes through Glacier Gulch and the Ice Lake, Hero Boy, Hero Girl and the Conductor return to the passenger car. Know-It-All tries to explain to Hero Boy what happened, unaware that he actually experienced more than he did, before Hero Boy heads to the observation car.
At the North Pole, when Hero Boy, Hero Girl and Billy are in the big bag of gifts, they find Know-It-All in the bag with them after he pulls on Billy's leg, probably thinking it was Christmas present. He explains that he is in the bag to make sure he will get everything he wants for Christmas, but that all he found was "a bunch of stupid underwear." They all get rescued from the bag by the elves after arriving at the center of the city. When Santa Claus speaks to the children, Know-It-All impatiently asks Santa to pick him as the one to receive the first gift, after which Santa tells him to be patient and show a bit of humility.
Before boarding the train for the ride home, his ticket gets punched again. He looks at it and reads "LEAN," though he is unaware that one of his fingers was covering the R and that it really says, "LEARN." The Conductor tries explaining his mistake, which makes him angry until he takes a second look at the ticket and sees the R. He apologizes for his outburst and the Conductor smiles. Like the other children, he wants to see Hero Boy's silver bell and feels sorry for him after finding out it got lost.
Before Billy gets off the train, Know-It-All questions why he is doing so until Billy explains that the train has stopped at his house. He also says goodbye to Hero Boy before he gets off the train, still feeling sorry about the bell. He points out, however, that, "It's the thought that counts."
- Know-It-All is one of many characters in the film to not be from the book.
- In the film, Know-It-All says that the train is a Baldwin 2-8-4 S3-class virtue type steam locomotive built at the Baldwin Locomotive Works in 1931 and weighs 456,100 pounds. In reality, the Baldwin Locomotive Works did built 35 locomotives of the S3-class for the Erie Railroad, which had the same wheel arrangement, but they were built in 1928 and weighed 457,500 pounds.
- "Yeah, I know it's a magic train. Actually, it's a Baldwin 2-8-4 S3-class virtue type steam locomotive built in 1931 at the Baldwin Locomotive Works. It weighs 456,100 pounds and..."
- "Hey, look, everybody! Herpolsheimer's! Herpolsheimer's!"
- "Boy, that guy sure likes to show off with his ticket punch. Look what that wise guy punched on my ticket. 'L-E.' What the heck does that mean?"
- "Ah, it's just another pick-up. That's weird. I thought you were supposed to be the last one."
- "He did!"
- "You know, Montezuma, the king of the Aztecs would drink 50 quarts of hot chocolate every day. It was thick as mud and red. He put chili pepper in instead of sugar. Get it? Hot chocolate?"
- "Hey, you missed it. We rode down some really sharp hills. And then, we were on what looked like a frozen lake. But I know it was just an optical illusion caused by moonlight atmosphere. He said the train was actually on the ice, but I said it was impossible because you can't put a train track... Hey, where you going now?"
- "Who gets the first gift of Christmas?"
- "Same as you, I'm checking out my Christmas presents. I want to make sure I've got everything on my list. All I got was one present and all I had was a bunch of stupid underwear!"
- "Hey, what gives? It was five minutes to midnight four minutes ago!"
- "Pick me! Pick me! I want the first gift! I want the first gift!"
- "'LEAN'? Whatever that's supposed to mean?"
- "Hey, are you saying I don't know how to...?! Oh. I'm sorry. It says 'LEARN'. My mistake."