Did you know that according to HappyCow.net all of these people are/were vegetarian or vegan?  (This is a partial list - they have almost 600 names listed.)

• Alanis Morissette
• Albert Einstein
• Alicia Silverstone
• Andre 3000
• Andy Dick
• Angela Bassett
• Anna Paquin
• Anne Hathaway
• Ariana Huffington
• Aristotle
• Ashley Judd
• Avril Levigne
• Barry White
• Belinda Carlisle
• Benjamin Spock, MD
• Bernadette Peters
• Bill Walton
• Billie Jean King
• Billy Joel
• Bob Barker
• Bobcat Goldthwait
• Bonnie Rait
• Boy George
• Brad Pitt
• Brandy
• Bridgitte Bardot
• Brooke Shields
• Bryan Adams
  
• Buddha
• Carrie Underwood
• Carrie Anne Moss
• Casey Affleck
• Cesar Chavez
• Chelsae Clinton
• Chris Evans
• Chris Martin
• Christian Bale
  
• Christie Brinkley
• Christina Applegate
• Christy Turlington
• Claudia Schiffer
• Coretta Scott King
• Corey Feldman
• Dario Argento
• Daryl Hannah
• Deepak Chopra
• Diane Keaton
• Dizzie Gillespie
• Doris Day
• Ed Asner
• Eddie Veder
• Edward Furlong
  
• Elijah Wood
• Ellen Degeneres
• Elvira Mistress of the Dark
• Erykah Badu
• Fiona Apple
• Forest Witaker
• Ganhi
• Gavin Rossdale
• George Harrison
• Gillian Anderson
• H.G. Wells
• Harriet Beecher Stowe
  
• Hayden Panettierre
• Heather Mills
• Henry David Thoreau
• James Cromwell
• Jamie Lee Curtis
• Jane Goodall
• Jared Leto
• Jason Mraz
• JD Salinger
• Jenna Jameson
• Jenny McCarthy
• Jim Carrey
• Joan Jett
• Joaquin Phoenix
  
• John Cleese
• John Lennon
• John Robbins
• John Tesh
• Joss Stone
• Julianna Margulies
• Kal Penn
• KD Lang
• Kate Winslet
• Keenan Ivory Wayans
• Kelly Clarkson
• Kelly Osbourne
• Kevin Eubanks
• Kevin Nealon
• Kim Basinger
• Kristen Bell
  
• KRS-One
• LaToya Jackson
• Leo Tolstoy
• Leonardo Da Vinci
• Leona Lewis
• Linda Blair
• Linda McCartney
• Lindsay Wagner
• Lisa Bonet
• Liv Tyler
• Lord Byron
• Louisa May Alcott
• Marilu Henner
• Mark Twain
• Mary Shelley
• Mary Tyler Moore
• Melanie Griffith
• Melissa Etheridge
• Michael Bolton
• Michael Jackson
• Mobey
• Morrissey
• Mr. (Fred) Rogers
• Naomi Watts
• Natalie Portman
• Nelly
• Nikola Tesla
  
• Olivia Newton John
• Omar Epps
• Orlando Bloom
• Pamela Anderson
• Paul McCartney
• Pauly Shore
• Peter Gabriel
• Peter Sellers
• Petra Nemcova
• Phylicia Rashad
• Pierce Brosnan
• Pink
• Plato
• Portia de Rossi
• Prince
• Raja Bell
• Ralph Waldo Emerson
• Ricky Lake
• Ringo Starr
• River Phoenix
• Rob Zombie
• Robert Redford
• Robin Gibb
• Rosa Parks
• Ru Paul
• Ruben Studderd
• Russel Simmons
• RZA
• Sade
• Samuel L Jackson
• Seal
• Sean Lennon
• Shannon Elizabeth
• Sinead O'Connor
• Sir Issac Newton
• Socrates
• Stella McCartney
• Steve-O
• Summer Phoenix
• Supreme Master Ching Hai
• Susan St. James
• Susan B. Anthony
• The Roots (all veg band)
• Thomas Alva Edison
• Tobey Maguire
• Tommy Lee
• Travis Barker
• Vanessa Williams
• Vanna White
• Vincent Van Gogh
• Voltaire
• Weird Al Yankovic
• Willem Dafoe
• Woody Harrelson
• Yoko Ono

Ref: http://www.happycow.net/famous_vegetarians.html