The Little Einsteins are the titular group of the series. They appear in every episode of the series.
- Leo is the leader of the Little Einsteins, and the one who pilots Rocket. He is Annie's big brother. His main talent is conducting and his most prized possession is his conductor's baton. Leo has red hair and green eyes. He wears green glasses. He is voiced by Jesse Schwartz and singing voice by Harrison Chad.
- Annie is a girl who loves to sing. She is Leo's little sister and the only character who has piloted Rocket alone. She loves animals, including dolphins and horses, but is afraid of spiders. She owns a silver microphone with orange music notes that she won in a singing contest. When she wishes to urgently point something out to the team, her usual phrase is "Look-look-look!" She has blonde pigtails tied in pink hairbows and blue eyes. She wears a green shirt with a blue denim dress and pink shoes in Season 1, and a light-blue shirt with a pink denim dress and light-blue shoes in Season 2. She is voiced by Natalia Wójcik.
- June is a young ballerina who loves to dance. She also enjoys looking at the stars at night with her telescope. She has dark brown hair and brown eyes. She wears a purple dress and pink headband. She is voiced by Erica Huang.
- Quincy is a boy musician who plays a variety of musical instruments, including the violin, flute, and trumpet. At some point in each episode, Quincy exclaims, "I cannot believe it!". He has dark brown hair and brown eyes. He wears a red and blue baseball cap, and a green and yellow T-shirt. He is voiced by Aiden Pompey.
- Rocket is the Little Einsteins' main mode of transportation, as well as their friend. Rocket has an array of tools and accessories that help the team complete their missions. Rocket also has the ability to transform into any other form of transportation, like a submarine or a train. Rocket communicates by making xylophonic noises.
The official ages of the characters
- Leo & June are 6 Years Old
- Quincy is 5 Years Old
- Annie is 4 Years Old
- Rockets age in unconfirmed but he may be 6 as he was on Leo's Baby Mobile in How We Became the Little Einsteins: The True Story.
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