Aaron Vail (1796–1878) was an American diplomat who served as chargé d'affaires in the United Kingdom and Spain in the 1830s and 1840s.

He was born in Lorient, France, where his father, Aaron Vail (1758–1813), a prominent businessman and merchant from New York was serving as U.S. consul and commercial agent.

The younger Aaron Vail was educated in Washington and became a clerk in the Department of State.

In 1831 Martin Van Buren selected Vail to be the secretary of the U.S. legation in London; when Van Buren's appointment as Minister was rejected by the United States Senate, Vail acted as chargé d'affaires, from April 4, 1832, until 1836.

He later lived in New York City; while in retirement, he declined diplomatic posts offered by Franklin Pierce and James Buchanan.