The self-portrait above is by Élisabeth Louise Vigée-Le Brun, a pupil of David who worked in the late 18th and early 19th centuries. It's one of a series of vexing and brilliant self-portraits in which the artist announces her babeness with delightful and unapologetic verve. (You can see more of them at the Art Renewal Center website, one of the Internet's great resources.)
Vigée-Le Brun was the teacher of Marie-Guillemine Benoist, who painted the amazing portrait below, which hangs in the Louvre:
I discovered Benoist's painting on Amy Crehore's web log Little Hokum Rag. Crehore once incorporated it whimsically into one of her own paintings:
Girlness is the central subject of most art, of course, but it has a pure sort of loveliness when executed by actual girls -- though I'm not sure quite why that should be.