As if actually having anxiety wasn't enough, Big Mouth Season 4 introduces a physical manifestation of the emotion in the form of Tito the Anxiety Mosquito, who latches onto the teens during their very awkward and tense stay at summer camp and follows them into the school year. There to balance out the pesky character is another new addition, Gratitoad, who helps the teens cope with this new, disorienting feeling. Tito is voiced by Maria Bamford, while Gratitoad is voiced by Zach Galifianakis.
Though Galifinakis is best known for his role in The Hangover movies and as the host of his satirical talk show Between Two Ferns, he's had a number of voice roles, such as Felix in Bob's Burgers, The Joker in the The Lego Batman Movie, and Mr. Link in the 2019 animated movie Mr. Link. He's one of several celebrity guest stars in Big Mouth Season 4, including Seth Rogen, Josie Totah, Lena Waithe, Quinta Brunson, John Oliver, Sterling K. Brown, Paul Giamatti, Maya Erskine, and Anna Konkle. Details of their roles were kept under wraps ahead of the premiere, but according to Netflix, Gratitoad's biggest responsibility to the Big Mouth teens is not letting anxiety "completely own them."
Season 4 premieres Dec. 4.