Mr. Reese is a tall, obese, middle-aged man who wears a green shirt, white undershirt, brown pants, and darker brown shoes, he is also balding and has a mustache.
Mr. Reese loves doughnuts and coffee, and he's usually seen to not be very serious, but in "Dream Boat" it's shown that he really does deeply care about his students succeeding, as Sumo's story about building a boat brought him to tears. Many episodes show that he personally dislikes Belson due to him being in detention all the time and for being extremely rude, however, in "Dingus & McNobrain", the two actually got along a little bit. In "Freedom Cactus", he loves Clarence's comic about the farting cactus, and he found it unfair when Ms. Shoop wished to censor it. In "The Substitute", it's shown that Mr. Reese doesn't know how to work the coffee machine, so he needs help from Ms. Baker to get his coffee.
In "Officer Moody", a bit of Mr. Reese's past is shown where he was a police officer working aside Carol Moody. It's shown that Moody was always annoyed by Jim's antics, such as the time when he made a "doughnut pancake" by mashing down a stack of doughnuts, and when he shoved the doughnut pancake into his mouth, he choked, causing chunks of the donuts to land on her papers, but the thing that bothered Moody the most was the time when Jim was on police duty and was late for the grand opening ceremony of the new children's library, Jim was distracted by his monkey wristwatch, which caused him to lose control of his car, and crash into the right side of the building, this made Moody so mad that she later fired him. After thinking back to that again, Mr. Reese started feeling like he's not good at doing anything, which lead him to believe he has no control of the students, especially Belson, until he discovered that he can break out of handcuffs with his butt, making him feel confident again, and he started reminding the students of his butt whenever he needs them to behave.
- Reese is voiced by Donovan Patton, who played Joe in Blue's Clues Season 5-Season 6. and voiced Bot on Team Umizoomi.
- In "Dream Boat" it is revealed he was a cop for about two years.
- In "Detention" it is shown that he easily succumbs to sugar, leading to "sugar crashes", Also known as "hypoglycemia".
- Same thing happened for the second time in "Big Boy".
- He is one of the few characters originally voiced by Skyler Page to not be voiced by Spencer Rothbell, however in "Straight Illin", he was voiced by the latter for only one time before being voiced Donavon Patton.
- He initially started out as a minor character, but when Season 2 came around, he became more prominent than he was in Season 1.
- in "The Substitute", it's revealed that his first name is Jim.
- In "Dare Day", it's shown that he once had a dog named Bandit, who died shortly, presumably after he was fired from the force.
- Mr. Reese has a similar personality to Miss Oddbod in Horrid Henry.