I loved Coach. He was just great. Nicholas Colasanto was just an absolutely perfect straight man.

From Wikipedia:
Following Colasanto's death the show's cast and crew honored him by hanging a portrait of Geronimo on the show's set. The picture had previously hung in Colasanto's dressing room behind the scenes. The picture had special meaning to him, and has been used at cast reunions to represent the actor. Sam straightens this picture on the wall at the end of the final episode of Cheers, in homage to both Colasanto and Coach.