Isaiah Dunn Clawson (March 30, 1822 – October 9, 1879) was an American Opposition Party / Republican Party politician who represented New Jersey's 1st congressional district in the United States House of Representatives from 1855 to 1859. He was elected as an Opposition Party candidate to the Thirty-fourth Congress and reelected as a Republican to the Thirty-fifth Congress, serving in office from March 4, 1855 to March 3, 1859, but was not a candidate for renomination in 1858.