Jonathan Winters, the rubber-faced comedian whose unscripted flights of fancy inspired a generation of improvisational comics, and who kept television audiences in stitches with Main Street characters like Maude Frickert, a sweet-seeming grandmother with a barbed tongue and a roving eye, died on Thursday at his home in Montecito, Calif. He was 87. His death was announced on his Web site, JonathanWinters.com.