Although there were a couple obscure early examples (Bee Palmer in 1929 and Marion Harris in 1934, both performing “Singing the Blues”), Eddie Jefferson is considered the founder, and premier performer of vocalese, the art of taking a recording and writing words to the solos, which Jefferson was practicing as early as 1949.
Eddie Jefferson’s first career was as a tap dancer but in the bebop era he discovered his skill as a vocalese lyricist and singer. He wrote lyrics to Charlie Parker’s version of “Parker’s Mood” and Lester Young’s “I Cover the Waterfront” early on, and he is responsible for “Moody’s Mood for Love” (based on James Moody’s alto solo on “I’m in the Mood for Love”). King Pleasure recorded “Moody’s Mood for Love” before Jefferson (getting the hit) and had his own lyrics to “Parker’s Mood,” but in time Jefferson was recognized as the founder of the idiom.
Jefferson worked with James Moody during 1955-1957 and again in 1968-1973 but otherwise mostly performed as a single. He first recorded in 1952 (other than a broadcast from 1949) and those four selections are on the compilation The Bebop Singers. During 1961-1962 he made a classic set for Riverside that is available as Letter from Home and highlighted by “Billie’s Bounce,” “I Cover the Waterfront,” “Parker’s Mood,” and “Things Are Getting Better.”