The search for Supergirl is on! The Hollywood Reporter has learned that Milly Alcock, best known for her work on HBO's 'Game of Thrones' spinoff 'House of the Dragon' as Princess Rhaenyra Targaryen, and Meg Donnelly, who starred in Disney Channel's hit musical franchise 'Zombies' have both screen tested for the role in Atlanta. Screen tests took place with DC Studios bosses James Gunn and Peter Safran present, and the field now narrowed to two.