Eben Jenks Loomis (November 11, 1828 – December 2, 1912) was an American astronomer, born in Oppenheim, New York. He attended the Lawrence Scientific School (Harvard) in 1851-53; was assistant in the American Ephemeris and Nautical Almanac office from 1850 until his retirement in 1900. During this time he also held the position of special assistant at the United States Naval Observatory in Washington, DC. He was the father of Mabel Loomis Todd.