There are at least 8 artists called "X".
These are photos from concerts where X played, so they may be of other bands that played the concert as well.
Iggy Pop / X / Boomtown Rats Nov 20, 1981 Los Angeles, California, United States Uploaded by Zimtrim
X / The Brat / No Alternative / Wilma Aug 8, 1981 San Francisco, California, United States Uploaded by Yvette Kay