Prior to the series' events, Mr. Bolhofner spent 15 years in the military. During that time, he also spent two months stranded inside a volcano eating lizards and his only tool being a pumice stone. Also, he has switched levels from being a seventh grade teacher to a sixth grade teacher and switched classrooms.
He is first seen in "Middle Men" when Lincoln Loud and Clyde McBride attend his class as part of their middle school orientation. When Lincoln and Clyde take Byron and Cici's assigned seats in this class, Mr. Bolhofner scolds Byron and Cici for not being in their seats and gives them zeros.
In "Hero Today, Gone Tomorrow", Mr. Bolhofner allows Margo Roberts a free pass out of a quiz for her victory over the Beaverton Bees which his ex-wife is the assistant coach of.
In "Schooled!", Mr. Bolhofner is now teaching his class in a wooden trailer that is poorly air-conditioned, where he has Lincoln and Chandler McCann as two of his students (due to Lincoln being unable to get a spot in Mrs. Salter's class with his friends because there's no room left). In addition, he has bad breath from the food he eats and owns a pet piranha named Hank. Once Lincoln returns to Royal Woods Middle School from Mapleton, Ontario, he persuades Mr. Bolhofner to turn down the thermostat a bit. To his classmates' surprise, Mr. Bolhofner obliges, saying nobody ever asked him to do that before.
In "Kernel of Truth", as part of Lincoln and friends attempting to revive the school's news program, Stella interviews Mr. Bolhofner about his birthday and suspected that he was in his 60s. Mr. Bolhofner angrily replies that he is 34 and slams the door. Principal Ramirez later states to Lincoln and his friends during her feedback of their revived news program that Mr. Bolhofner is suing the school.
In "No Bus No Fuss", Rita Loud accidentally pulls Vanzilla out in front of Mr. Bolhofner's car which angers him causing Lincoln to duck out of sight. While in the cafeteria, Mr. Bolhofner cuts in front of Lincoln telling him to considers both of them even for this morning's incident. He also advises Lincoln to tell his mom that he says hi.
In "Flying Solo", Mr. Bolhofner becomes the head of the school's home-economics club, which Stella, Rusty, and Zach joined, hoping to make cookies. After mentioning that he once survived in the Amazon Rainforest, Mr. Bolhofner states that they will be making cricket cheesecakes. Mr. Budden later contracted the home-ec club to make the outfits for the glee club. For Lincoln and Clyde, they got survivalist-type outfits that were the ideas of Zach and Mr. Bolhofner as both of them give each other the thumbs up.
Mr. Bolhofner's most prominent role in the series to date came in the episode "Rumor Has It". In it, he has to bring Lincoln and his friends on the fifth-grade field trip due to the school bus that's taking the rest of the class being too full for all of them. However, his car suffers a blow-out in the woods, so he brings the gang to his hunting cabin in the woods. Lincoln and his friends, however, fear that Bolhofner plans to kill them because of rumors they've heard about him being either an escaped convict, a cannibal, and/or a convict. They manage to escape his cabin, but Mr. Bolhofner then fights off a bear to rescue them, thus revealing to them that he actually isn't the bad guy that the rumors made him out to be, and that he himself dislikes the fact that all the students think of him that way. The next day, Lincoln and his friends show the other students that Mr. Bolhofner saved their lives, something he deeply appreciates.
Mr. Bolhofner is a very strict and rude teacher, who punishes his students for minor misdeeds, like not being in their assigned seats during his classes. However, he has also a cool side, as he allows successful athletic students to pass without quizzes, and as mentioned above, will protect students from dangerous animals. Despite his short temper and strictness, he is willing to change things that do not bother him like turning down the temperature in his class when Lincoln asked.
He is a tall, dark tan-skinned man. He has dark greasy hair, two thick black eyebrows, and a black mustache. He wears a light yellow polo shirt, with a green stripe across it, green trousers, with a black belt buckled in, and brown shoes.
In Season 5, he now has a sloppy appearance where is now sporting facial hair, his hair is much messier, his shirt is stained, and his pants now have a patch on it, in addition to his shoes tops being taller, resulting in them sticking out of his pants.