Celebrity Transformations Relive Birthday Girl Sarah Michelle Gellar's Best Beauty Moments Through the Years By InStyle Editors InStyle Editors Facebook Instagram Twitter Our editors and writers comprise decades of expertise across the beauty, fashion, lifestyle and wellness spaces in print and digital. We prioritize journalistic integrity, factual accuracy, and also having fun with every story we share. InStyle's editorial guidelines Published on April 14, 2015 @ 07:14AM Pin Share Tweet Email Photo: Michael Buckner/Getty Images, BURSTEIN/GLOBE PHOTOS, INC Happy birthday, Sarah Michelle Gellar! The now 38-year-old actress, beloved for kicking major butt in Buffy, taking an evil turn in Cruel Intentions, and terrifying moviegoers with films such as I Know What You Did Last Summer and The Grudge. She has also kept busy with more recent TV stints on The Crazy Ones, Ringer, and lending her voice to the animated series Robot Chicken. Not only has the star tried her hand at a medley of genres in her career, but she is also no stranger to experimenting with her hair and makeup looks. From staying on-trend with '90s fads (hello, dark lipstick and blossom-bedecked hat!) to sporting beachy blonde waves, see Gellar's standout beauty moments through the years. PHOTOS: Sarah Michelle Gellar's Transformation