He has light skin, freckles, and light brown hair with some of it swept upward. Melvin wears glasses, a white collared shirt, a red bowtie, a yellow vest, shorts, and brown shoes.
In the movie, the frame of Melvin's glasses are green, his bowtie is a golden yellow color, and he sports a watch.
Captain Underpants: The First Epic Movie
He first appeared in the Invention Convention, where he introduces his latest invention, the Turbo Toilet 2000. However, things went awry when George and Harold tampered with the Turbo Toilet 2000, reprogramming it to shoot out toilet papers. However, Melvin was able to catch them in the act thanks to another invention of his, the Tattle Turtle (a toy turtle with a nanny cam hidden inside). In order to get extra credit, Melvin turned over the Tattle Turtle's footage to Mr. Krupp, who then decided to put George and Harold in separate classes for the rest of the school year as punishment for their pranks and to annihilate their friendship.
Later, after Professor Poopypants got himself hired as the new science teacher, he noticed that Melvin was the only student who never laughed at his silly name. After studying his brain, Poopypants discovered that Melvin's brain lacked the gland that causes laughter, which is why he has no sense of humor. Upon making this discovery, Melvin and Poopypants decided to team up to rid the world of laughter. To do this, they took the Turbo Toilet 2000 and used Poopypants's Size Ray to enlarge it into a giant battle mech. They then took rotten leftovers from the school cafeteria to use as the Turbo Toilet's power source.
Later, Poopypants arrived at the school in the Turbo Toilet and began his conquest to eliminate laughter. He'd rigged the Turbo Toilet with a giant ray gun powered by none other than Melvin, which used the energy from his brain to fire laser beams that erased a victim's sense of humor. By this method, Poopypants and Melvin turned all the students (except George and Harold) into humorless zombies. Captain Underpants tried to stop them, but was quickly subdued due to not having any actual superpowers. However, while the Turbo Toilet was busy beating up Captain Underpants, George and Harold climbed on top of the robot and tried to reason with Melvin to get him to stop Poopypants. However, Melvin simply alerted Poopypants to their presence, after which he zapped them. However, the beam didn't seem to have any effect on George and Harold, so Poopypants upped the power of the laser. When that didn't work, Poopypants scanned their brains and discovered that their laughter glands were enormous, so he increased the power even more, and eventually started to get to them. However, Poopypants accidentally restored their sense of humor by saying "Uranus," which was the first thing they'd laughed at together. Meanwhile, Captain Underpants, having been swallowed whole by the Turbo Toilet, drank some of the toxic toilet water and got superpowers from it, which allowed him to break out and attack the Turbo Toilet, causing it to malfunction and shoot toilet paper everywhere just like at the Invention Convention. Also, the ray gun exploded because Poopypants overloaded it with power, which restored everyone's sense of humor and sending Melvin falling to the ground. Melvin survived this but was crushed by a roll of giant toilet paper. He survived this as well, only to get rolled away as the kids started partying and pushing the rolls around for fun.
- Despite being the smartest kid in school, he failed to notice that Mr. Krupp is wearing a toupee to hide his baldness problem.