This is a disambiguation page.
It points to other pages that have similar names. If you followed a link here, please fix it to point to one of the pages listed below.
Planet X may refer to:
In-universe
- Planet X (Famine on Planet X) - The planet featured in the Doctor Who annual short story Famine on Planet X
- Planet X (Risk Assessment) - A planet mentioned in the Torchwood novel Risk Assessment
- Planet X (Planet X) - The planet featured in the Bernice Summerfield audio story Planet X
Real world
- Planet X - the second story in The New Adventures of Bernice Summerfield Volume 3: The Unbound Universe