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.
Urgh! A Music War / Dead Kennedys / Bad Brains / X / Cramps / Chelsea Aug 15, 1980 Santa Monica CA Uploaded by Stephenhuerta
Circle Jerks / X / Alley Cats / Urinals / Gun Club May 9, 1980 Redondo Beach, California, United States Uploaded by Evan Rude
The Boomtown Rats / X Apr 20, 1980 Los Angeles, California, United States Uploaded by Wicked Goddess
Circle Jerks / X Apr 4, 1980 San Diego, California, United States Uploaded by Evan Rude