Lonergan is a surname. Notable people with the surname include:
Andrew Lonergan (born 1983), English football goalkeeperArthur Lonergan (1906–1989), American art directorAugustine Lonergan (1874–1947), U.S. Representative from ConnecticutBernard Lonergan, (1904–1984), Canadian Jesuit Priest, philosopher-theologian, economistDan Lonergan, Australian sports commentator and writerDean Lonergan, New Zealand rugby league player and current events promoterJennifer Lonergan, Canadian educator and nonprofit business executiveJohn Lonergan (1839–1902), Union Army captain in the American Civil WarKate Lonergan (born 1966), British actressKenneth Lonergan (born 1962), New York playwright, screenwriter, and directorLenore Lonergan (1928–1987), stage and film actress during the 1930s and 1940sLloyd Lonergan (1870–1937), New York scenario and screenwriterMike Lonergan, American basketball player, coachRichard Lonergan (1900–1925), American underworld figure and labor racketeerSam Lonergan (born 1987), Australian Football playerTom Lonergan (Australian footballer) (born 1984), Australian rules footballerTom and Eileen Lonergan, married couple of American Peace Corps volunteers who went missing in 1998 and are presumed deadWalter Lonergan (1885–1958), second baseman in Major League Baseball