Dominique-Napoléon Saint-Cyr was a politician in Quebec, Canada and a two-term Member of the Legislative Assembly of Quebec (MLA).
He was born on August 4, 1826 in Nicolet, Centre-du-Québec and was an educator.
He ran as a Conservative candidate in the district of in the provincial district of Champlain in 1875 and won. He succeeded François-Xavier-Anselme Trudel.
Saint-Cyr was re-elected in 1878, but did not run for re-election in 1881. He was succeeded by Conservative Robert Trudel.
He died on March 3, 1899 in Quebec City.