S2, E15: After Grace's (Debra Messing) dad, Martin (guest star Robert Klein), is rushed to the hospital with a bleeding ulcer, Grace is shocked when he refuses to take Will's (Eric McCormack) blood for a transfusion. When Will's mom, Marilyn (guest star Blythe Danner), finds out, she uncharacteristically takes Martin to task. Karen's (Megan Mullally) demands for Jack's (Sean Hayes) wedding, along with upstaging him during his one-man show, cause Jack to uninvite Karen from his wedding.