Louis-Henri Blais (June 9, 1827 – August 21, 1899) was a lawyer and political figure in Quebec.
He represented Montmagny in the Legislative Assembly of Quebec from 1867 to 1871 as a Liberal.
He was born in Montmagny, Lower Canada, the son of Louis Blais and Marie-Madeleine Noël.
Blais was educated at the Collège de Sainte-Anne-de-la-Pocatière, was called to the Quebec bar in 1851 and set up practice in Montmagny.
He was president of the Agricultural Society for Montmagny County.