Martin Scorsese

Bill Murray

John Hurt

David Bowie

Glenn Close

Jim Parsons
Emily Blunt
Whoopi Goldberg
Mickey Rooney
John Krasinski
Dave Grohl

David Hasselhoff

Salma Hayek

Stan Lee

Bruce Campbell
Lucy Lawless

Totoro

Chris Evans

Carrie Fisher

Tom Cruise
Steven Spielberg
Gwyneth Paltrow
Danny DeVito
John Travolta
Nathan Lane
Britney Spears

Janet Leigh

Thomas Jane and Clifton Collins Jr.

Brett Favre

Hugh Jackman

Gene Hackman

Tony Bennett
Hugh Bonneville
Sean "Diddy" Combs
Celine Dion
Lady Gaga
Josh Groban
Salma Hayek
Tom Hiddleston
Tom Hollander
Frank Langella
Ray Liotta
James McAvoy
Miranda Richardson
Saoirse Ronan
Til Schweiger
Russell Tovey
Danny Trejo
Stanley Tucci
Christoph Waltz

Martin Scorsese

Flik and Heimlich from A bug's life

Ricki Lake
John Waters
Adam Shankman
Marc Shaiman
Scott Wittman

Erin Brockovich (as a waitress named Julia)

Jordan Belfort

Peter Jackson

Huey Lewis

Leonard Nimoy

Eurovision stars:

John Lundvik
Anna Odobescu
Bilal Hassani
Loreen
Jessy Matador
Alexander Rybak
Jamala
Elina Nechayeva
Conchita Wurst
Salvador Sobral

Jack Skellington
Donald Duck

Natasha Lyonne

Martin Scorsese

Edgar Bergen
Milton Berle
Mel Brooks
James Coburn
Dom DeLuise
Elliott Gould
Bob Hope
Madeline Kahn
Carol Kane
Cloris Leachman
Steve Martin
Richard Pryor
Telly Savalas
Orson Welles
Paul Williams

Billy Crystal
Anjelica Huston
Fred Willard
Dana Carvey

Elliot Gould
Julie Christie

Helena Bonham Carter

Art Carney
James Coco
Dabney Coleman
Gregory Hines
Linda Lavin
Joan Rivers
Elliott Gould
Liza Minnelli
Brooke Shields
Sesame street characters: Big bird, Bert and Ernie, Grover, Count Von Count, Cookie monster

Peter Ustinov
Robert Morley
Peter Falk
Eric Rohmer
Oscar the grouch
Jim Henson (as himself)

Ethan Hawke

Human cameo: Paul Rudd

Cameos from other IPs:

Batman
E.T.
Shrek
Randy Marsh (South Park)
Flounder (The little mermaid)
Roger Rabbit
Butthead (Beavis and Butthead)
He-Man and Skeletor
My little pony
Pumbaa
Jimmy Neutron
Lumiere (Beauty and the beast)
The three little pigs
Phineas & Ferb
Scrooge McDuck
Baloo (the jungle book)
Garfield
Darkwing Duck
Frozone (The incredibles)
Foghorn Leghorn
Roger Rabbit
BOB (Monsters vs. Aliens)

Eddie Izzard
Joe Cocker
Salma Hayek
Bono

Mart Crowley (author of the original play The boys in the band)

Rupert Everett

John Huston

David Lynch

Robert Duvall

Lauren Bacall
Humphrey Bogart

Mathieu Amalric

Burt Reynolds
James Caan
Liza Minnelli
Anne Bancroft
Marcel Marceau
Paul Newman

Julie Newmar
Naomi Campbell
Quentin Crisp
Miss Coco Peru
Robin Williams
RuPaul
Joey Arias
Lady Catiria
Miss Understood
Candis Cayne
Hedda Lettuce
Lady Bunny
José Sarria

the Farmer from Shaun the sheep

Droopy the dog

Idina Menzel (the original Elphaba in the Broadway show)
Kristin Chenoweth (the original Glinda in the Broadway show)
Winnie Holzman (writer of the musical book for the Broadway show)
Stephen Schwartz (composer)

John Hurt
Hugh Hefner
Bea Arthur
Carl Reiner
Barry Levinson
Jackie Mason
Fritz Feld
Sidney Lassick
Nigel Hawtorne
Johnny Silver
John Hillerman

Anne Bancroft

Dua Lipa
John Cena
Rob Brydon
Nicola Coughlan
Ann Roth

Burt Bacharach
Elvis Costello
Will Ferrell
Woody Harrelson
Willie Nelson
Rebecca Romijn
Charles Napier
Kristen Johnston
Jerry Springer
Tim Robbins
Fred Willard

Herbie Hancock
Wayne Shorter
Esperanza Spalding
Antonio Sánchez
Gary Clark Jr.
Robert Glasper

Carrie Fisher
Pink
Eve
Bruce Willis
Mary-Kate Olsen
Ashley Olsen
Jaclyn Smith

Robert Englund (as the bus driver in the opening scene)