Tricia Helfer is a Canadian actress and former model, best known for her role as Number Six in the re-imagined Battlestar Galactica miniseries and television series.

Helfer was born and raised in the rural community of Donalda in Stettler County, Alberta. She was raised on her family's grain farm and at the age of 17, while standing in line at a local movie theatre, she was discovered by modeling agency scout Kelly Streit. She is of Norwegian, Swedish and German descent.

In 1992, she won Ford Models' Supermodel of the World Contest and was subsequently signed to the Elite Model Management and later to Trump Model Management. Tricia retired from fashion modeling in 2002 and states that all her shoots since then are related to projects or product endorsements. She has appeared in ad campaigns, including Ralph Lauren, Chanel, and Giorgio Armani. Helfer has walked for top fashion shows such as Carolina Herrera, Christian Dior, Claude Montana, Givenchy, John Galliano, and Dolce & Gabbana. She has graced the covers of Flare, Amica, ELLE, Cosmopolitan, Marie Claire, and Vogue, among others. She also regularly appeared in photo shoots by Maxim magazine, was the magazine's wall calendar girl for 2005, and was ranked #57 on the Maxim's Hot 100 Women of 2007. She also posed topless, but not entirely nude, for the February 2007 issue of Playboy.

While working in New York as a model, Helfer hosted a Canadian television fashion program Ooh La La. She relocated to Los Angeles in 2002 to pursue a full-time film career. Her first acting assignment was a co-starring role as Sarah on the television series Jeremiah. Thereafter she played the role of a model, Ashleigh James, in the May 16, 2002 episode "The Hunger Artist" on CSI: Crime Scene Investigation. In 2002, Helfer played the female lead, Eva, in the independent film White Rush. In 2003, she was chosen to play Number Six, a humanoid Cylon operative, on Battlestar Galactica. Concurrent with her role in Battlestar Galactica, Helfer began producing and hosting Canada's Next Top Model on May 31, 2006. The same year, she appeared in the motion pictures Spiral and The Green Chain.

In October 2006, it was announced that Helfer would not return to host the second season of Canada's Next Top Model in order to concentrate on her work on Battlestar Galactica. Helfer also played a major role in Electronic Arts Command & Conquer 3: Tiberium Wars, as the high-level Nod general Kilian Qatar, along with her Battlestar Galactica co-star, Grace Park She also starred in the episode "Roadkill" on the second season of the American paranormal drama TV series Supernatural.