Robert Downey Jr.
Dr. John Dolittle
Harry Collett
Tommy Stubbins
Michael Sheen
Dr. Blair Müdfly
Jim Broadbent
Lord Thomas Badgley
Antonio Banderas
King Rassouli
Jessie Buckley
Queen Victoria
Emma Thompson
Poly (voice)
Rami Malek
Chee-Chee (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)