Maria Shriver-Kennedy Quimby is Rainier Wolfcastle's wife.
Maria is first seen with her ex-husband, attending Freddy Quimby's 18th Birthday Party at Mayor Quimby's house, where she tries to comfort him when he started feeling depressed from the failure of his then-recent movie, especially his being reminded of its failure by both Bart and Chief Wiggum.
Sometime between then and when Bart first met Rainier's daughter, Greta Wolfcastle, they apparently got a divorce. Right after Bart met Greta, Rainier tells his daughter that her mother's custody battle starts at 6:00pm.
Maria is seen marrying Rainier again, when Homer bursts in with a camera.