Born Ethel Hilda Keeler in Nova Scotia, the former Mrs. Al Jolson is best known today for appearing in several Busby Berkeley musicals, beginning with 1933's 42nd Street, which made her an overnight success. Like many starlets, Ruby Keeler got her start under the aegis of Florenz Ziegfeld before migrating to Hollywood.
I'll be honest with you--it took me a little bit to warm up to Ruby Keeler. She didn't seem like much of an actress at first, but she's so face-meltingly cute that I couldn't help but like her more and more each time I saw hew in a picture (it's easy to see why Al Jolson was so smitten with her). Her aura of charming naivete makes her a perfect fit for the role of the ingenue.
The above photo comes from Shadow Waltz, a nifty little tribute site dedicated to Ruby.