Prisoner X
Prisoner X may refer to:
Placeholder name for prisoners
- Ben Zygier, held in Ayalon Prison in Israel until his death there in 2010
- *Ali-Reza Asgari, incorrectly asserted to be Prisoner X by the Tikun Olam blog
- Avri Elad, the "third man" or "X" in the Lavon Affair, held in Ayalon Prison
- Marcus Klingberg, held from 1983 to 2003 in Israel
- Prisoner X2, an unidentified prisoner held in Ayalon Prison from about 2004 until 2018
- Tomer Eiges, or "Officer X", died in military prison awaiting trial in 2021