Keegan-Michael Key

Buddy / Dark Buddy (voice)

Cristin Milioti

Grace

Delaney Quinn

Freddy

Caleb Williams

Wade

Madison Skyy Polan

Hannah

Tristan Borders

Oliver

Patton Oswalt

Strappy (voice)

Jimmica Collins

Betty Bunny / Scared Flower (voice)

Eric Bauza

Mr. Mailbox / Worry Well / Couchy / Trashy / Pee Flower (voice)

Topher Grace

Ben

Bryson JonSteele

Derek

Seamus Flynn

Timothy

Luke Speakman

Josh

Bennie Taylor

Mailman Miles

Phuong Kubacki

Nurse Nancy

Devon Hawkes Ludlow

Charlie the Train (voice)

Michael Shannon

Willie (voice)

Clint Howard

George

Sergey Zhuravsky

Buddy (Suit)

Jonathan Yurco

Dark Buddy (Suit)