Seth Hastings (April 8, 1762 – November 19, 1831) was a United States representative from Massachusetts.

Born in Cambridge in the Province of Massachusetts Bay to Seth and Hannah (Soden) Hastings, he was a descendant of the colonist Thomas Hastings who came from the East Anglia region of England to the Massachusetts Bay Colony in 1634.

He graduated from Harvard University in 1782, studied law, was admitted to the bar in 1786 and commenced practice in Mendon, Massachusetts.

Hastings was elected as a Federalist to the Seventh Congress to fill the vacancy caused by the resignation of Levi Lincoln.

He declined to be a candidate for renomination in 1806 and was a member of the Massachusetts State Senate in 1810 and 1814.