John Michael O'Keefe, known as Johnny O'Keefe (19 January 1935 – 6 October 1978), was an Australian rock and roll singer whose career began in the 1950s. Some of his hits include "Wild One" (1958), "Shout!" and "She's My Baby". In his twenty-year career, O'Keefe released over fifty singles, 50 EPs and 100 albums.

Often referred to by his initials "J.O.K." or by his nickname "The Wild One", O'Keefe was the first Australian rock 'n' roll performer to tour the United States, and the first Australian artist to make the local Top 40 charts. and He had twenty-nine Top 40 hits in Australia between 1959 and 1974.