Xavier Riddle and the Secret Museum

• Xavier Riddle (voiced by Aidan Vissers) – Xavier is the leader of his group with his sister Yadina and their friend Brad. He appears to be an excitable kid who is eager to go back in time and meet various historical figures. He is described as a kid who loves everything (especially art and basketball), but lives for adventures.
• Yadina Riddle (voiced by Zoe Hatz) – Yadina is Xavier's younger sister. She seems to be eager to explore the secret museum and learn about various historical figures. She carries a stuffed turtle around with her named Dr. Zoom. She is quite talented, whether it be with books or with balls. Although Yadina is very extroverted (not a wallflower at all), she is only six years old. This means that she can be very honest with just about anyone, and sometimes even blunt. For example, Yadina dislikes meanness of any kind, and if anyone is not being friendly to another, Yadina will let them know exactly what she thinks of their behavior. When faced with conflict, Yadina is an expert at making others understand a situation from someone else's perspective, which ultimately requires empathy, self-awareness, and self-regulation. She also has a habit of making bad puns, which she fruitlessly tries to explain to both her brother Xavier and her buddy Brad.
• Brad Scott Meltzer (voiced by Wyatt White) – Brad tends to be the most nervous and neurotic of his friends and suffers from several allergies. He is sometimes hesitant to go on adventures since travelling back in time makes him dizzy. Brad is quite partial to butterflies, as well as action heroes and is a relatively good artist who enjoys drawing comic book stories. He is described as having "delusions of averageness", and is apprehensive over everything. His friends, Xavier and Yadina, encourage him to live a little and to try new things. He suffers from imposter syndrome. Brad is Jewish, as revealed in the episode I am Tomioka Tossai, when he shows his friends a dreidel. His last name is only revealed on the website. He is an avatar of the author of the book series Brad Meltzer, whom he also resembles.

• Berby – A small, egg-shaped flying robot who resides at the Secret Museum and functions as part of the time machine by transporting Xavier, Yadina and Dr. Zoom, and Brad back and forth in time. Berby communicates by making robotic beeping sounds, and is good friends with the kids and Dr. Zoom. It also functions as the museum's curator, ensuring all of the exhibits are taken care of and in the right places. Berby also appears in all the shorts after all episodes, either racing around the world with Xavier, playing hide & seek with Dr. Zoom & Yadina, co-starring with Brad in one of his "Bradman" comics, or going on random travels with Dr. Zoom. It is also revealed in "I Am Madam President" that Berby is a female robot.

A TV special titled Xavier Riddle and the Secret Movie: I am Madam President aired on March 16, 2020. In the special, Yadina, who dreams of becoming president one day, realizes all the presidents were men.[9] She questions if she can still be president, even though it is something no girl has done yet. The trio visit the Secret Museum, where a five-part star is shown to them. They travel to different periods in time, where they meet women who are attempting to do something that has never been done before. Yadina learns from them on what is needed to do something that has never been done before, as she attempts to complete the star. She meets Jackie Joyner-Kersee, Amelia Earhart, Junko Tabei, and Sally Ride.[10]

Joyce Slaton of Common Sense Media gave Xavier Riddle and the Secret Museum a mixed review. She stated that "the show makes many historical inaccuracies, which makes it odd for a TV show that wants to make history come back alive for kids." She also stated that "the show's tendency to play too fast and loose with the historical facts is confusing, and that 'Go for it!' is an unlikely motto for Amelia Earhart, who deceased in 1937 and didn't complete her solo Atlantic flight as a grade school student, as Xavier depicts." George Washington Carver did have a secret garden as a child, in which he learned important lessons that impacted his career in botany. But, as Slaton states, "it's a real stretch to imagine him having to defend plants from renegade soccer players in 19th century Missouri," and that "the show seems to overlook his importance as an activist for ex-slaves and champion of sustainable agriculture, instead boiling his messages down to 'take care of plants and you'll take care of the earth.'" [12]