Olaüs Thérien (September 3, 1860 – December 31, 1929) was a Canadian lawyer, editor and political figure in Quebec, Canada.
He represented Montcalm in the House of Commons of Canada from 1887 to 1891 as a Conservative member.
He was born in Ste-Anne-des-Plaines, Canada East, the son of Pierre Thérien and Claire Derouin, and was educated at the Petit Séminaire de Saint-Thérèse and Université Laval.
He was called to the Quebec bar in 1885.
Thérien was defeated when he ran for reelection in 1891.