Martha Stewart has made history as the oldest Sports Illustrated Swimsuit cover model ever, appearing on the cover at the age of 81. The other three cover models this year are Megan Fox, Kim Petras and Brooks Nader, and Stewart's cover shot features her with tousled hair and a glamorous look. This year's issue is set to hit stands later this week, and Stewart's appearance is a testament to her longevity in the media and her ability to remain relevant in a constantly changing industry.