Robert Downey Jr.

Dr. John Dolittle

Harry Collett

Tommy Stubbins

Michael Sheen

Dr. Blair Müdfly

Jim Broadbent

Lord Thomas Badgley

Antonio Banderas

King Rassouli

Rami Malek

Chee-Chee (voice)

Jessie Buckley

Queen Victoria

Emma Thompson

Poly (voice)

John Cena

Yoshi (voice)

Kumail Nanjiani

Plimpton (voice)

Craig Robinson

Kevin (voice)

Ralph Fiennes

Barry (voice)

Tom Holland

Jip (voice)

Octavia Spencer

Dab-Dab (voice)

Selena Gomez

Betsy (voice)

Marion Cotillard

Tutu (voice)

Kasia Smutniak

Lily Dolittle

Carmel Laniado

Lady Rose

Frances de la Tour

Dragon (voice)

Jason Mantzoukas

James the Dragonfly (voice)

Ralph Ineson

Arnall Stubbins

Joanna Page

Bethan Stubbins

Sonny Ashbourne Serkis

Arnall Stubbins Jr.

Oliver Chris

Sir Gareth

Clive Francis

Archbishop

Paul Holowaty

Navy Man

Elliot Barnes-Worrell

Captain William Derrick

Mark Umbers

Lieutenant

David Sheinkopf

Don Carpenterino

Sid Sagar

Jeff the Prisoner

Martin Pemberton

Postman

Tim Treloar

Humphrey the Whale (voice)

Jim Carretta

Beard Mouse and Leona (voice)

Nick Fisher

Mini the Sugar Glider (voice)

Matt King

Clyde

Ranjani Brow

Mouse (voice)

Kelly Stables

Mouse (voice)

Scott Menville

Army Ant (voice)

Gia Davis

Baby Animal (voice)

Henry Holcomb

Baby Animal (voice)

Kyrie McAlpin

Baby Animal (voice)

Isley Zamora

Baby Animal (voice)

Stewart Scudamore

Pirate

Samson Kayo

Pirate

John-Luke Roberts

Pirate / Animal Performer

Joseph Balderrama

Prisoner

Daniel Hoffmann-Gill

Prisoner

Jane Leaney

Animal Performer

Josh Jefferies

On Set Chee-Chee / Animal Performer

Shaun McKee

On Set Yoshi / Animal Performer

Richard Soames

Animal Performer

Will Arnett

Rabbit (voice) (uncredited)