Seymour Lane Dwinell (November 14, 1906 – March 27, 1997) was an American manufacturer and Republican politician from Lebanon, New Hampshire. Born in 1906 in Newport, Vermont, he served in and led both houses of the New Hampshire legislature before his tenure as the 69th governor of New Hampshire from 1955 to 1959. He died in 1997 aged 90 in Hanover, New Hampshire and is buried in Lebanon, New Hampshire.