Jacob Tremblay as Orion (voice)

Paul Walter Hauser as Dark (voice)

Angela Bassett as Sweet Dreams (voice)

Colin Hanks as Adult Orion (voice)

Natasia Demetriou as Sleep (voice)

Golda Rosheuvel as Unexplained Noises (voice)

Nat Faxon as Insomnia (voice)

Aparna Nancherla as Quiet (voice)

Ike Barinholtz as Light (voice)

Carla Gugino as Orion's Mom (voice)

Matt Dellapina as Orion's Dad (voice)

Nick Kishiyama as Tycho (voice)

Mia Akemi Brown as Hypatia (voice)

Shannon Chan-Kent as Adult Hypatia (voice)

Jack Fisher as Richie Panici (voice)

Werner Herzog as Narrator (voice)

Sky Alexis as Lisa (voice)

Hira Ambrosino as Woman at the Drive-In (voice)

Yoshi Ando as Man at the Drive-In (voice)

Larisa Asuaje as Mrs. Spinoza (voice)

Sean Charmatz as Irene's Boss / Cucumber Dentist / Soda / Insomnia Guy 1 (voice)

Walt Dohrn as Stray Cat / Insomnia Guy 2 (voice)

Ren Hanami as Adult Sally (voice)

Amy Hill as Irene (voice)

Alyssa Lee as Irene's Daughter / Insomnia Girl (voice)

Noah McCown as Scared Child (voice)

Shino Nakamichi as Sally (voice)

Aliki Theofilopoulos as Irene's Coworker / Mom / Juice Box / Insomnia Teacher (voice)

Toru Uchikado as Insomnia Man (voice)