Paul Terry

Character: James Henry Trotter

Miriam Margolyes

Character: Aunt Sponge / Glowworm (voice)

Joanna Lumley

Character: Aunt Spiker

Pete Postlethwaite

Character: The Magic Man

Simon Callow

Character: Grasshopper (voice)

Richard Dreyfuss

Character: Centipede (voice)

Jane Leeves

Character: Ladybug (voice)

Susan Sarandon

Character: Miss Spider (voice)

David Thewlis

Character: Earthworm (voice)

Steven Culp

Character: James' Father

Susan Turner-Cray

Character: James' Mother

Cirocco Dunlap

Character: Girl with Telescope

Kathryn Howell

Character: Woman in Bathrobe

Mike Starr

Character: Cop

Michael Girardin

Character: Reporter #1

J. Stephen Coyle

Character: Reporter #2

Tony Haney

Character: Reporter #3

Mario Yedidia

Character: Street Kid

Jeff Mosley

Character: Hard Hat Man

Jeff Bennett

Character: Centipede (singing voice) (uncredited)

Sally Stevens

Character: Glowworm (singing voice) (uncredited)