Oscar's Pop is the father of Oscar the Grouch & Oscar's brothers, Ernest & Otto & their sister Bunny. Like Otto, Mr. Grouch is never seen in any episodes of Sesame Street. He only mentioned in the 1976 book How to Be a Grouch, along with a few other of Oscar's relatives. He is also mentioned in the Christmas special A Special Sesame Street Christmas. Whether Mr. Grouch has passed away or whether he & Oscar's mother are divorced is unknown.