Isaac Ledyard (November 5, 1755 or 1754 – August 28, 1803) was a physician and politician from New York.
He was born in Groton, Connecticut, the son of Youngs Ledyard (1731–1762) and Mary (Avery) Ledyard (1730–1787).
He was Health Officer for the Port of New York. Ledyard was a presidential elector in 1800, voting for Thomas Jefferson and Aaron Burr.
The town of Ledyard, Connecticut is named for his family.