This gap-toothed, tousle-haired comic lead and character player first came to prominence as a star of the Broadway stage. After training at the American Theatre Wing in the early 1950s, Morse made his Broadway debut in "The Matchmaker" (1955), starring Ruth Gordon and gained attention for his turn in the play "Say, Darling" (1957). He segued to musicals co-starring with Jackie Gleason and Walter Pidgeon in "Take Me Along" (1959), based on Eugene O'Neill's "Ah, Wilderness!" and achieved stage stardom in the leading role of J. Pierpont Finch in the award-winning "How to Succeed in Business Without Really Trying" (1961), which earned him a Tony Award. In "Sugar" (1974), a musical based on Billy Wilder's "Some Like It Hot", Morse assumed the role created by Jack Lemmon. Over a decade later, Morse re-ignited his career with a tour-de-force portrayal of author Truman Capote in the one-man play "Tru" (1990), which earned him a second Tony Award.
Morse has worked sporadically in features since his 1956's debut in "The Proud and the Profane". He reprised two of his best stage roles, Barnaby Tucker in "The Matchmaker" (1958) and Finch in "How to Succeed in Business Without Really Trying" (1967). Morse offered comic turns as a Brit overseeing his uncle's funeral in Tony Richardson's "The Loved One" (1965) and as Walter Matthau's best friend extolling the joys of infidelity in Gene Kelly's "A Guide for the Married Man" (1967). After appearing in Disney's "The Boatnicks" (1970), he disappeared from the big screen for seventeen years, re-emerging in the unfunny comedy "Hunk" (1987).
Since the mid-50s, Morse has also appeared on the small screen. He and E.J. Peaker co-starred in the musical/comedy series "That's Life" (ABC, 1967-68), which depicted the life of a young married couple in songs, sketches and monologues. Morse was a frequent guest on series ranging from "Naked City" to "The Red Skelton Show" to "The Hollywood Squares". In 1992, he recreated his performance as "Tru" for PBS and won an Emmy as Best Actor in a Miniseries or Special. In addition to providing voices for animated shows, Morse has also appeared in the ABC miniseries "Wild Palms" (1993) and portrayed Grandpa in the TV remake, "Here Comes the Munsters" (Fox, 1995). His daughter Robin is an actress.