Emilio Mendoza is one of Greg Heffley's classmates who appeared in Diary of a Wimpy Kid: Old School. Emilio was the boy who spotted Gareth Grimes' tooth when it got stuck in Rowley's forehead. Mr. Jefferson told him to get the Nurse for help. Emilio was also the one who sneaked a pancake from the breakfast table, so he could mail it away to his mom, in order to show her how bad the food was at the camp.
Later, when the group was walking through the woods, a cabin-mate named Gareth Grimes tripped on a rock sticking out of the ground, and when Emilio saw that the rock had scrapes on it, he got really upset. He said that the only one that could be responsible for THAT was Silas Scratch. Another of Greg’s cabinmates, named Jeffrey Swanson, said that the rock may have marked Silas Scratch's grave. But Greg said that if that was true, then Silas Scratch would have had to bury himself. A rumor was then started that Silas Scratch was an UNDEAD farmer that couldn't be killed.
Greg had borrowed Emilio's glasses to try to start a fire by reflecting the rays of the sun. But Greg forgot to return the glasses to Emilio, and he accidentally crushed them between his and Jeffrey Swanson's hands during a high-five. Emilio is as blind as a bat without his glasses on, as he smacks into a tree.
Towards the end of the trip, Greg's cabin is desperate to get rid of the stench in their room. So when someone suggests raiding a girl's cabin for deodorant, the one who is the most excited about the idea is Emilio. But Greg says that he can't come, as his lack of proper sight would be a handicap. Then Emilio says that his sense of SMELL was really good, so he would actually come in handy of the mission. When Greg's cabin-mates run him through a blindfolded smell test, he gets every one right. And sure enough, when they are lost in the woods, his sense of smell directs them to the nearest girl's cabin. In a hurry to run back to their cabin from the girl's cabin, they forgot that they left Emilio behind as he was stumbling around in the dark groping at a tree, which is how Mrs. Graziano found him after she opened her cabin door. As a result, Greg's group was found out as the people in the raid.
- He is very blind without his glasses.
- He probably has a great sense of smell since he guessed the smell of items, all correctly, in a smell test his group gave him, before his group went on a raid of the girls cabins. He also smelled the girls cabins from a good distance when his group went on a raid of the girls cabins.
- His name might come from Italy, since Emilio is a Italian name.
- Mariana Mendoza might be related to him due to both of them sharing the same last name, however this could just be a coincidence.
- Diary of a Wimpy Kid: Old School (First and only appearance)