 Jeffrey Dean Morgan reappeared as the deceased Denny Duquette in Izzie's hallucinations due to a brain tumor.Former series regular Kate Walsh returned to the show with a special guest star billing as Dr. Addison Montgomery along with fellow "Private Practice" stars Audra McDonald portraying Naomi Bennett, Taye Diggs in the role of Sam Bennett and Grant Show portraying Dr. Archer Montgomery.Tyne Daly also appeared receiving a special guest star in the role of Carolyn Maloney Shepherd, Derek's mother, while Héctor Elizondo appeared as Carlos Torres, Callie's father.