Milly Alcock as styled by Felicity Kay, wearing Balenciaga and Cartier. (Photo via Milly Alcock IG) If Hollywood needed a new It girl with a little edge and a lot of style power, Milly Alcock might have just flown in to claim the title. Fresh off her breakout role as Rhaenyra Targaryen in House of the Dragon, Alcock is now standing in an entirely different kind of spotlight as Kara Zor-El in Supergirl. This time, she is trading royal gowns for punk-rock rebellion in a cape.