Pierre Alphonse de Tonty, or Alphonse de Tonty (1659 - 10 November 1727) was an officer who served under the French explorer Cadillac and helped establish the first European settlement at Detroit, Michigan, Fort Pontchartrain du Detroit on the Detroit River in 1701. Several months later, both Cadillac and Tonty brought their wives to the fort, making them the first European women to travel so deep into the new territory.

Tonty was commanding the fort in Detroit by 1717, but by 1727 numerous complaints, including those by the Huron led to his dismissal.

Tonty was involved in numerous scandals and disreputable activities before he was eventually dismissed from his post as commandant of Fort Ponchartrain. He died before he could obtain another appointment or return to France.