Ilisia (Greek: Ιλίσια pronounced [iˈli.si.a]) is a neighborhood of Athens, Greece, named after the river Ilisos.

Ilisia is named after the Ilisos river, which rises near Kaisariani on the slopes of Mount Hymettus and which, although Athens' historic river, is barely noticeable except in heavy rain.

The name originally used for the villa of Sophie de Marbois-Lebrun, Duchess of Plaisance (Villa Ilisia), that was built near Ilisos river in 1848.

Although the name Ilisiakos seems to mean "team of Ilisia", the spelling, with Greek letter H (Ηλυσιακός) instead of I (Ιλισιακός), refers to Elysium (Ἠλύσιον πεδίον).

The rationale for this is that the club aims to represent a wider area from Ilisia.