Luc and Theo are best friends in the 8th Grade who get stuck in a time loop where every day is the same Monday but they rock it like it's Saturday. Luc is a twelve-year-old boy always looking for fun. After a major sucky school day he makes things worse by hopping on his skateboard and crashing into Theo's garage-lab. Chemicals mix, sparks fly and 17 scientific experiments mash into one freaky mess. The results: Luc and Theo find themselves caught in an irreversible time-loop. This would be a problem if the boys weren't having so much fun. Looped is every kid's dream. Theo and Luc may be stuck in a time-loop repeating the day Monday, October 12th 2015, over and over again. Now, their options are limitless. This provides them with only one over-riding challenge: How much fun can two kids squeeze into one Monday?
- Lucas "Luc" Maxwell - (voiced by Mac Heywood in the pilot, and Lyon Smith in episodes) A goofy and dim-witted 12-year-old boy, who crashed his skateboard into his friend's machine, causing the loop to happen. Luc enjoys doing destructive things without facing consequences, but if the loop doesn't reset his wrongdoings, he often forgets that it'll go away the next coming Monday.
- Theodore "Theo" Merton Jr. (voiced by Bryn McAyley in the pilot, and Kevin Duhany in episodes) smart, inventive 12-year-old, who invented a machine that would experiment with time travel. His friend crashed into it, causing the loop to happen. Theo carefully documents all the events of the repeating day, learning how to do what he wants to do.
- Jesse - The school bully, who's main weapon is to lock his victims in a wooden box and fart on them. These victims would mainly be Luc and Theo, due to Luc's tendency to spill his pizza on his shoes every Monday, despite his advantage. Although he's as rough and tough, as he says he is, he has a soft side for animals, and wouldn't dare even eat them, causing him to be a vegan.
- Gwyneth (also known as Gwyn for short) - A pink-haired nerdy girl at Port Doover Elementary, who Theo has a crush on. Gwyn is completely indifferent to Theo and shows a bit of slight toward him as well. She doesn't even know his name and always mistakes his name for something else. She does, however, have a huge crush on Luc, to the point of a stalkerish obsession.
- Sarah - The pretty, popular girl at the school. She is saving her voice for a talent show, on Friday, so she refrains from speaking until then. She communicates by texting her twin henchgirls, Kelly and Kelli, so that they may translate her word.
- Kyle Bush - The most popular and well beloved boy in Port Doover Elementary. He is an overly perfect, handsome, caring, giving, fantastic boy, who is strongly despised by Luc, completely out of jealousy.
- Kelly and Kelli - Twin sisters, who serve Sarah hand and foot. They serve as her mouthpieces and fulfill all of her greedy desires. The only difference between the two is the arm their bracelets are on.
- Amy - A creepy goth girl at Port Doover Elementary, who mainly resigns in the basement of the school. She's a ethically ambiguous frenemy of Luc and Theo, being helpful to them in dire situations, and blatantly rude to them at other times.
- Principal Applecrab - The scrawny, dorky principal of Port Doover Elementary. At the school assembly, he sneezes for just long enough for Luc and Theo to switch out his plans and make some other completely ridiculous event happen.
- Mr. LemonJello - Luc and Theo's homeroom teacher. He is a very boring man, who seems to be just as emotionally drained as his students. He uses fancy, complicated words in dialogue, which are projected through a plain, monotone voice.
- Coach Lessard - The overweight, out of shape gym teacher, who's means of transportation are driving around the school on a golf cart. He is obsessed with getting students to sign up for badminton tryouts, but unfortunately, none of them are interested.
- Jan Itor - The school janitor with a high muscle mass, but a low intelligence. He works hard, cleaning the mess of messes in Port Doover Elementary, but just before his well-earned break, Luc always throws a pizza slice at him, forcing him to spend five minutes cleaning it up, cutting into his Gloulash Burrito time. He is also secretly a pro wrestler.
- Claire - The bossy, obnoxious, overbearing babysitter of Luc, who's unwillingly watching over him while his parents are away for three days. The loop is happening on the second day, meaning that she's pretty much always going to be his guardian. She's not only a horrible babysitter, but a dreadful driver, getting into car accidents and causing collateral damage everywhere she goes.
- Lester - A nerdy, video game and TV obsessed boy, who spends the majority of his school days, voluntarily stuffed in his locker, after spilling his frozey freeze on Jesse. After school, he secretly larps with aliens, in a role-switching battle between the Earthlings and the Zerms.
- Jerry Rivers - Port Doover Elementary's school news channel reporter. He gives out great and passionate reports on extremely boring events, such as the tightening of the loose screw on the Wilt Doover statue and his nanny's newly knitted quilt. He is also a stupid klutz, who ends off every report with "This is Jerry Rivers, singing off." A mistake he keeps idiotically falling into, loop aside.
- Glee Club Kids - A three little kids with no names given.
- Alianna - An action-packed, kick-butt alien girl in disguised as a human, who larps with Lester. Like how she's won every game she's played with Lester, she's also won the heart of Luc Maxwell, who manages to make her his girlfriend in a few episodes. However, due to the loop, Luc has to keep repeating the action of making her his girlfriend, in order to keep their relationship going.
- Tommy Sparkle - An egotistical, self-absorbed wizard, who declaes himself the greatest magician in the universe. He lives in a magic realm, outside of the plane of normality, but can be summoned into the real world, every time someone says "I am the greatest magician in the universe", so that he may descend from the magic clouds and put them up to the test, needing always to prove himself to be the best.
- Toni - The lovely assistant of the lovelier magician, Tommy Sparkle. She helps him out with everything he needs, but never gets any thanks or gratitude. In fact, she is always the butt of all his tricks, getting herself physically maimed, bruised, disfigured, and injred by almost all of his fancy tricks.
- McGal and Spritz - Two time travelling police officers of an organization called the "Time Fuzz", who arrest all criminals who are breaking the laws of time. Luc and Theo are their primary target, for their looping of the same Monday is illegal. Only problem is, they have no idea it's them. The two of them have developed a friendly bond with Luc and Theo, and have never been able to put the two together, realizing that they're the only leftover suspects, who they have not tested for unethical abuse of time travel.