The Haldimand Affair was a series of negotiations conducted in the early 1780s between Frederick Haldimand, the British governor of the Province of Quebec, his agents, and several people representing the independent Vermont Republic.

Sir Frederick Haldimand, KB was a Swiss military officer best known for his service in the British Army in North America during the Seven Years' War and the American Revolutionary War. From 1778 to 1786, he served as Governor of the Province of Quebec, during which time he oversaw military operations against the northern frontiers in the war, and engaged in ultimately fruitless negotiations to establish the independent Vermont Republic as a new British province. His administration of Quebec was at times harsh, with the detention of numerous political dissidents and agitators.