Oscar
Elliott Smith
Hedgehog
Oona Laurence
Susie (voice)
Julia Pott
Pepper
Sam Lavagnino
Lucy (voice)
Indie Nameth
Alice (voice)
Charlyne Yi
Max (voice)
Ramone Hamilton
Oscar (voice) / Baby Dylan (Alice) (voice)
Antonio Raul Corbo
Additional Voices
Jeremy Crutchley
Jimjams (voice) / Mortimer (voice) / Mortimer
Bobby Moynihan
Mildred
Faye Larkin
Additional Voices (voice) / Puddle (voice) / Boyband (voice)
Ethan Maher
Ava (voice) / Additional Voices (voice) / Mrs. Goose (voice)
Fortune Feimster
Pajamas (voice) / Additional Voices (voice)
Naomi Hansen
Oscar (voice)
Asher Bishop
Betsy (voice) / Betsy / Sarah (voice)
Nikki Castillo
Oliver (voice) / Additional Voices (voice) / Decent Boi (Hedgehog) (voice)
Andre Robinson
Alexa (voice)
Alexa Nisenson
Additional Voices (voice) / Ghost Dad Cole (voice) / Alligator Chef (voice)
Cole Sanchez
Blanche (voice) / Butter Goth (voice) / Cinnamon Raisin Toast (voice)
Alia Shawkat
Howard (voice)
Mike Birbiglia
Margot (voice) / Additional Voices (voice) / Margot
Kimiko Glenn
Additional Voices (voice) / Chet (voice) / Ghost Dad Kent (voice)
Kent Osborne
Ramona (voice) / Ramona / Emma (voice)
Lesley Nicol
Barb (voice)
Whoopi Goldberg
Moon (voice) / Additional Voices (voice)
Cedric the Entertainer
Andy (voice) / Additional Voices (voice) / Monster Under the Bed (voice)
Alfred Molina
Additional Voices (voice) / Langston / Waylon (voice)
Kevin Michael Richardson
Additional Voices (voice) / Tammy (voice) / Tammy
Roz Ryan
Shark (voice) / Hedgehog's Dad (voice) / Additional Voices (voice)
Richard Kind
Sue (voice) / Oscar's Mom (voice)
Kathleen Wilhoite
Additional Voices (voice) / Alien (voice)
Rylee Alazraqui
Stuart (voice) / Additional Voices (voice) / Prime Monister (voice)
Stephen Root
Mallory (voice)
Jo Firestone
Sandy (voice) / Toothpaste (voice) / Puffer Fish (voice)
Maria Bamford
Saxophone (voice)
Elijah Wood
Additional Voices (voice) / Basketball (voice)
Luke Lowe
Prophecy Alien (voice) / Patootie (voice) / Additional Voices (voice)
Max Mitchell