Isabel Boyer Gillies (born February 9, 1970) is an American author and actress. She is best known for her role as Kathy Stabler, Elliot Stabler's wife, on Law & Order: Special Victims Unit. Her memoir, Happens Every Day, was a New York Times bestseller. Her most recent book is titled Cozy.

Isabel is a lifelong New Yorker and worked as an actress for many years. She is the author of A Year and Six Seconds and Starry Night, a young adult novel about first love. Her work has been featured in various prominent publications including Vogue, The New York Times, Real Simple, Cosmopolitan, and Saveur.

She currently resides in Manhattan with her husband, kids, and their dog, Maude.