Thomas Amory Deblois Fessenden, (January 23, 1826–September 28, 1868) was a U.S. Representative from Maine and brother of Treasury Secretary William Pitt Fessenden.

Born in Portland, Maine, he attended North Yarmouth Academy and Dartmouth College and graduated from Bowdoin College in 1845. He then studied law and was admitted to the bar in April 1848. He established a practice in Mechanic Falls, Maine, and moved to Auburn, Maine in 1850, where he continuing working as an attorney.

He was a delegate to the Republican National Convention in 1856 and 1868 and a member of the Maine House of Representatives in 1860 and 1868, as well as prosecuting attorney for Androscoggin County in 1861 and 1862.

He elected as a Republican to the 37th Congress to fill the vacancy caused by the resignation of Charles W. Walton and served from December 1, 1862, to March 3, 1863, and was not a candidate for renomination in 1862.

He returned to Maine and resumed the practice of law. He died in Auburn, and is interred in Riverside Cemetery, Lewiston, Maine.