Ilg is a surname. Notable people with the surname include:
Alfred Ilg (1854–1916), Swiss engineer Bernhard Ilg (born 1956), German politician Dieter Ilg (born 1961), German musician Frances Ilg (1902–1981), American pediatrician Konrad Ilg (1877–1954), Swiss trade unionist and politician Patriz Ilg (born 1957), German steeplechaser