Lithgow won Best Guest Actor in a drama at Saturday's Creative Arts Emmys for his bone-chilling role as a serial murderer on Showtime's Dexter.
Lithgow, 64, credited his chemistry with onscreen nemesis Michael C. Hall for bringing the character to terrifying life – and said Hall is "doing very, very well" since revealing in January that he was in remission from Hodgkin’s lymphoma.
"There were about four days over the course of that season last year that I had to work as hard as Michael does every day," Lithgow told reporters after winning his Emmy. "He's had no trouble this season working five days a week, so I'm delighted."
Lithgow also offered reporters a puzzled reaction to his onstage gaffe – in accepting the award, he thanked rival network HBO rather than Showtime.
"I said HBO?" he said afterward. "I'll never live that down."
Reporting by NINA TYLER and CYNTHIA WANG