Henri Gagnon (French pronunciation: [ɑ̃ʁi ɡaɲɔ̃]; 6 March 1887 – 17 May 1961) was a Canadian composer, organist, and music educator.
He spent 51 years playing the organ at the Notre-Dame Basilica-Cathedral of Quebec City where, according to music historian François Brassard, he earned "a prestige similar to that of the famous organists of Europe."
He began studying solfège and piano with his father at the age of eight and he remained his principal teacher until he was thirteen.
In 1908 and 1909 he was a soloist in the Concerts Touche, and he also filled in for Gigout occasionally as organist at the Église Saint-Augustin de Paris.
In 1958 the National Film Board of Canada made a 30-minute documentary, Henri Gagnon, organiste, profiling his life and career.
Reboulot notably plays his own work, Variations sur le nom d'Henri Gagnon, on the recording.