The Most Happy Fella is a 1956 musical with a book, music, and lyrics by Frank Loesser. The story, about a romance between an older man and younger woman, is based on the 1924 play They Knew What They Wanted by Sidney Howard. The show is described by some theatre historians and critics as operatic. The original Broadway production ran for 14 months and it has enjoyed several revivals, including one staged by the New York City Opera.
It is remembered as having been the subject of a series of back to back segments featuring three of its main scenes as broadcast in a live telecast of the Ed Sullivan show on Sunday, October 28, 1956, the night of Elvis Presley's second appearance on that show. That appearance went on to be seen in some 168 stations in North America and garnered a 34.6 rating, a 57% share, with an estimated audience of 56.5 million viewers, as per Trendex, the precursor of Nielsen.