Pierre Eugène Lafontaine (November 26, 1857 – April 21, 1935) was a lawyer, educator, judge and political figure in Quebec.

He was born in Saint-Édouard, Canada East, the son of Laurent-David Lafontaine and Edwige Singer.

He was admitted to the Quebec bar in 1879 and practised in Montreal with Raymond Préfontaine and then Frédéric Liguori Béique.

He died three years later in Montreal at the age of 77 and was buried in Notre Dame des Neiges Cemetery.

Lafontaine was the author of Droit romain published in 1912 and contributed to la Revue légale and Thémis.