Saint-Léonard-d'Aston (French pronunciation: [sɛ̃ leɔnaʁ dastɔn]) is a municipality in Nicolet-Yamaska RCM in the province of Quebec, Canada.

The municipality is situated along Route 155, partway between Drummondville and Trois-Rivières.

Autoroute 20 and a major intercity railway line, part of Canadian National Railway over which VIA Rail Canada passenger trains also operate, cross through the town.

Until the completion of the northern branch of Autoroute 55 in October 2006, Saint-Léonard-d'Aston was a common waypoint for those who travelled between Trois-Rivières and Sherbrooke.

Population Population trend:[5] Language Mother tongue language (2006)[6] Along Autoroute 20, on the Rang du Moulin-Rouge, there stood an impressive structure called the Manoir Bigfoot—also known as the Restaurant Madrid—which was notable for its bizarre decorations: large monster trucks parked outside next to a line of larger-than-life statues of dinosaurs.