Louis-Onésime Loranger (April 7, 1837 – August 18, 1917) was a Canadian lawyer, politician, and judge.

Born in Yamachiche, Lower Canada, the son of Joseph Loranger and Marie-Louise Dugal, Loranger was educated in Montreal at the Petit Séminaire de Montréal and studied law at the Collège Sainte-Marie.

He was called to the Bar of the Province of Canada in 1858 and practiced law with his brothers, Thomas-Jean-Jacques and Jean-Marie.

He was also a member of the Montreal City Council for the ward of Saint-Louis from 1871 to 1877.

In 1882, he was appointed a judge in the Superior Court of Quebec for the district of Montreal.