The word Eidolon means "ideal" or "ghost" and can refer to several things:
- Eidolon Software is a software company that caters to NextStep and Mac OS X clients.
- An eidolon is an astral double of a living being.
- Eidolons are spirits that are central to the plot of Final Fantasy IX.
- The Eidolon was a computer game from the 1980s by Lucasfilm Games
- The Eidolons are also a species of alien in the series Farscape.
- Eidolons are also the most advanced form of zombie under the control of Dr. Vahzilok in the MMORPG City of Heroes.
- Eidolon was an Australian magazine about science fiction and fantasy: no longer published in paper, but continues online .
- Eidolon is the name of the oldest and most powerful of the 3 Serpent Riders in the Heretic-Hexen series.
- Eidolon is a genus of bat in the family Pteropodidae.