Stephen Wallace Dempsey (born May 8, 1862) was a Republican member of the United States House of Representatives from New York. He represented New York’s 40th congressional district and served as a federal legislator during the early twentieth century. His service in Congress is documented under the biographical identifier D000229.

Dempsey began his tenure in the U.S. House of Representatives on December 6, 1915, and remained in office until March 3, 1931. Over the course of these years, he served eight terms as a representative, reflecting sustained electoral support in his district. Throughout this period, he held the formal role of Representative from New York, aligned with the Republican Party.

During his time in Congress, Dempsey served as a historical member of that body, participating in national legislative affairs as part of New York’s delegation. He left office as a former member in 1931, concluding more than fifteen years of continuous service in the House.