|First Appearance (Barney and the Rocko Squad)||Einsteins at the Base|
|Barney and the Rocko Squad Portrayer||Jesse Schwartz|
- "Alisa's snoring... June is snoring... Annie's snoring...but we need more POWER!!!!"
- — Leo noticing that Alisa Bosconovitch, June, and Annie are fast asleep.
Leo is a 6-year-old boy, the Little Einsteins leader, and can be similar in personalities with the Rocko Squad leader, Evil-Man. He is Annie's big brother, and is not to be confused with the Leo from Alisa's Adventures in Rockoland. His main talent is conducting and his most precious object is his baton (he never comes to Rockoland without it). His skills with the baton include the ability to awaken Alisa Bosconovitch and Ling Xiaoyu, the female Tekken: Blood Vengeance protagonists, with a slight zap.
Jesse Schwartz, who previously voiced Leo in Little Einsteins, voices Leo again in Barney and the Rocko Squad.