U.S. actress and comedienne Rosie O'Donnell is to guest star on four episodes of the drama series "The Fosters," ABC Family announced Tuesday. O'Donnell -- a foster and adoptive parent in real life -- will play Rita Henricks, a social worker at Girls United, the group foster home where Maia Mitchell's character, Callie, ends up after running away, the network said in a news release. O'Donnell will appear in four episodes this season, starting Monday.