“House of Dragon” star Milly Alcock has signed on to play “Supergirl” in James Gunn's DCU. Deadline reports that the role was basically down to just two actresses: Alcock and Meg Donnelly. Alcock prevailed, and that’s a good thing. As tepid as my interest in Gunn’s “Supergirl” is, I do have to admit that Alcock was far and away the best thing about the otherwise forgettable “House of Dragon.” I hear she’s also great in the show “Upright.” She’s a real talent.