Bill Nye

"The Science Guy"; Science Communicator, TV Presenter & Mechanical Engineer; Climate Change Activist

George Takei

Actor, Social Justice Activist & Social Media Mega-Power

Samantha Bee

Host of "Full Frontal" on TBS & Former Correspondent at "The Daily Show" With Jon Stewart

Retta

Stand-Up Comedian & Actress Known for "Parks and Recreation"

Tracee Ellis Ross

Actress, Producer; Chief Executive Officer at PATTERN

Max Greenfield

Actor Known For "New Girl" & Children's Author

Giancarlo Esposito

African-Italian American Actor, Director, Producer; Best Known for his Role as Gustavo "Gus" Fring on AMC's Breaking Bad

John Hodgman

Resident Expert on "The Daily Show with Trevor Noah", Author, Humorist

Jon Stewart

Talk Show Host, Comedian & Producer

Earth (the Book): A Visitor's Guide to the Human Race. Written and Edited by Jon Stewar...

Nick Offerman

Actor, Writer & Carpenter; Best Known for "Parks and Recreation"

Paul Reiser

Actor, Writer & Stand-Up Comedian Known for Portraying Paul Buchman in "Mad About You"

Henry Winkler

Actor, Producer, Director & Best-Selling Author; Best Known for "Happy Days"

Helen Hunt

Academy & Emmy Award-Winning Actress Known for Her Roles in "As Good as It Gets" and "Mad About You"

Arnold Schwarzenegger

Actor, Producer, Director, Writer; California’s 38th Governor; Host of "Celebrity Apprentice"

John Cho

Actor Known for "Harold & Kumar" Series & "Star Trek" Reboot Series

Brooke Shields

Actress; Model; Women's Health, Aging & Mental Wellness Advocate

Alyssa Milano

Actress, Author, Philanthropist & Founder of Touch by Alyssa Milano; Known for "Charmed" and "Who's the Boss"

Demi Lovato

Grammy Nominated Singer-Songwriter, Musician, Philanthropist & Mental Health Advocate

Demetri Martin

Comedian & Actor Known for Netflix's "The Overthinker;" Former Contributor on "The Daily Show"

Bret Michaels

Singer-Songwriter, Musician & Reality Television Personality