Otto Osworth is a young orphan and one of the main characters of Time Squad, and has appeared in every episode except "Recruitment." He used to live in an orphanage run by the nun cruel Sister Thornly, who punished him for reading, which is what he enjoyed most. He was "adopted" (admittedly kidnapped) by the Larry 3000 and Officer Buck Tuddrussel when they miscalculated on a mission to find Eli Whitney. He was more than willing to leave the orphanage and became an unofficial member of the team in "Eli Whitney's Flesh-Eating Mistake".
Although Otto has an enormous memory of history in nearly every field, deep down he is still a child, and easily gets along with Tuddrussel's immature, childlike attitude. In truth, he is the only member of the team to actually enjoy the history aspect of his job. Otto is the conscience of the group. He's always wanting to the right thing and becomes quickly angered by Tuddrussel and Larry's selfishness and will not put up with the crazy and absurd antics of historical figures. He often finds himself to be the only one capable of handling the mission, sometimes solving the problem with psychological methods. Other times he has to resort to trickery and pranks. Though a self proclaimed book worm, and shown as being a weak child, Otto can sometimes enjoy activities such as fishing and playing baseball. Also it has been mentioned once that he has a natural talent for shooting with a gun and knows a little karate.
Otto wears a blue t-shirt, black shorts, red and white shoes and giant, black circular-framed glasses. Has red hair and freckles, with eyes that appear to be dark green as well. He is only seen without his glasses in "Out With The In Crowd," where his eyes are just squints. Otto is short in stature, and apparently will be at almost the same height when he is an elderly man, seen in "Old Timers Squad."
- Otto's appearance is based on that of Sherman from "Mr. Peabody and Sherman".
- Nobody knows what happened to Otto's parents.
- Otto is voiced by Pamela Segall Adlon, who is famous for voice roles of crossdressing voices (for boys, such as Andy Johnson from "Squirrel Boy", and Lucky from "101 Dalmatians: The Series".) as well as tomboyish female characters (Ashley Spinelli from "Disney's Recess" Margaret Rose "Moose" Pearson from "Disney's Pepper Ann").
- Sherman (Mr. Peabody and Sherman)
- Mac (Foster's Home for Imaginary Friends)
- Lewis (Meet the Robinsons)