Sanja Milkovic Hays is a Croatian costume designer.

Following her graduation from the University of Zagreb's architecture programme, she started working as an assistant to American, British, and Italian costume designers at Jadran Studios in Zagreb. In 1987, she took a plane to Los Angeles, California, where she continued to work with chef Joseph Porro as an assistant costume designer on films including Stargate, Stargate, and Independence Day.

She worked on costumes for Stephen Norrington's Blade and Jonathan Frakes' Star Trek: Insurrection in 1997. She also collaborated with directors John Singleton, Tim Story, and Brian De Palma. She has worked with Justin Lin and Lee Tamahori on several occasions.

She successfully contributed to the creation of Rob Cohen's projects in the 2000s, including The Fast and the Furious and most notably The Mummy: The Tomb of a Woman.