Henri O'Kelly (full name: Joseph Pierre Henri O'Kelly) (23 June 1859 – 15 March 1938) was a Franco-Irish composer, pianist, organist and choir director, based in Paris. A minor composer in the Impressionist school, as a conductor he made outstanding contributions to French church music.
Henri O'Kelly was the second child (first son) of Joseph O'Kelly's (1828–1885) first marriage (1856). He was born in Paris and grew up in Rue du Faubourg Poissonnière in the 9th arrondissement. After initial piano studies with his father, he enrolled at the Conservatoire de Paris (1874–79) studying solfège with Albert Lavignac (1874–76) and piano with Georges Mathias (1876–79). O'Kelly was an exceptional student, winning awards every year, always sharing them with his fellow students Claude Debussy and Gabriel Pierné. While Debussy never won a "premier prix" in piano, O'Kelly did in his final year, 1879. The somewhat unexpected birth of a son in 1881 forced him to abandon a promising pianistic career and seek financial safety as a church organist and choir master, holding such positions at Saint-Germain-l'Auxerrois in central Paris (1881–1900) and Saint-Vincent-de-Paul in the 10th arrondissement (1900–1918). O'Kelly also taught music at the École Rocroy (10th arrondissement) from at least 1906 into the 1930s, having previously obtained the titles of "Officier d'Académie" (Silver Palm) in 1899 and "Officier de l'Instruction Publique" (Golden Palm) in 1901. Finally, from at least 1888 through the mid-1920s, O'Kelly was involved with the well-known piano manufacturer Pleyel where from c.1907, he was one of the pianists recording pianola rolls (see below).