Heather Marks was born in Calgary, Alberta, and was discovered at the Calgary Woman's Show. She won the Mode Models model search at the age of twelve and has since done shows and advertisements for Karl Lagerfeld, Calvin Klein and other prominent fashion designers. She has appeared on the covers of magazines such as Vogue, Dazed, French and Mixte. She was recently cast in the 2006 Victoria's Secret show, which will air on CBS in December, 2006.
Marks is known in the fashion world for her big eyes and "doll-like" features. Along with Gemma Ward, Caroline Trentini, Lily Cole, Lisa Cant, Jessica Stam, and Devon Aoki, she is part of the rising trend of models with these "doll-like" or "elfin" features. They are called "baby dolls" or "baby doll aliens" by internet fans.