Danaids. To find out more about the crimes and the punishment of the daughters of Danaus, see this Wikipedia article: link; for information about the image: image source.
The Danaids were the fifty daughters of King Danaus. They were betrothed to the fifty sons of the king's brother, but there was no love lost between the two brothers. On orders from King Danaus, all but one of the fifty daughters murdered their new husbands on their wedding night (Hypermnestra was the one exception). As a punishment, the Danaids were condemned for all eternity to try to fill a tub with water; as you can see, the tub has holes in it, so they can never manage to complete their task.