Ilium is a fictitious town in eastern New York state, used as a setting for many of Kurt Vonnegut's novels. "Ilium" was the Roman name for Troy; it was presumably chosen by Vonnegut to fit in with the other classically-named towns in upper New York, such as Syracuse and Ithaca.

Player Piano (1952) places Ilium southeast of Albany and Rensselaer, probably within Albany County near what is today Interstate 90. North of Albany, on the same railway line, is Cohoes, longtime residence of Vonnegut's character Kilgore Trout.