Cat Deeley

Self - Host

Stephen 'tWitch' Boss

Self

Matthew Morrison

Self

Maksim Chmerkovskiy

Self

Allison Holker

Self - Judge

Nigel Lythgoe

Self - Judge

Mary Murphy

Self - Judge

Adam Shankman

Self - Judge

Paula Abdul

Self - Judge

Jason Derulo

Self - Judge

Mia Michaels

Self - Judge

JoJo Siwa

Self - Judge

Jeanine Mason

Herself

Janette Manrara

Self

Vanessa Hudgens

Self - Judge

Lauren Sánchez

Self - Host

Leah Remini

Self

Alan Bersten

Himself

Tate McRae

Self

Teddy Coffey

Self - Contestant

Rihanna

Self - Performer

Alex Wong

Himself - Contestant

Brian Friedman

Dan Karaty

Fergie

Wade Robson

Lady Gaga

Ryan Conferido

Timbaland

Natasha Bedingfield

Lloyd

Daddy Yankee

Debbie Allen

Mika

Self - Musical Guest

Ryan Cabrera

Jordin Sparks

Katy Perry

Ellen DeGeneres

Katie Holmes

Ciara

Benji Schwimmer

Travis Wall

LL Cool J

Heidi Groskreutz

Jaimie Goodwin

Lev Cameron

Self

Maddie Ziegler

Self - Judge

Courtney Platt

Herself

Drew Barrymore

(archive footage)

Roger L. Jackson

(archive footage)

David Arquette

Adam Sandler