Biography: Tiffani Thiessen (born Tiffani-Amber Thiessen; January 23, 1974) is an American actress best known for her roles as Kelly Kapowski in Saved by the Bell and as Valerie Malone in Beverly Hills, 90210. She is also known for her role on Fastlane as Wilhelmina 'Billie' Chambers. As of 2009, she plays...