Special Forces is a pretty broad term that a lot of celebrities were technically in. I've heard a lot of definitions of special forces. My interpretation of special forces is someone who is trained to go behind enemy lines. Basically Infantry goes straight up to the line and special forces are the people trained to go behind enemy lines.
http://www.ranker.com/list/6-and-famous-people-who-were-technically-in-the-special-forces/stokified,
Jesse Ventura
Navy SEAL
John F. Kennedy
Special Boat Operator Officer, Went Behind Enemy Lines
Mark Burnett
Parachute Regiment British Army
Mirko Filipović
Croatian Special Forces
Randy Couture
Army Airborne
Rudy Boesch
Navy SEAL
Bear Grylls
British SAS