| artist,genre,country | |
| X RELIGION,Symphonic Prog,Uzbekistan | |
| X-LEGGED SALLY,RIO/Avant-Prog,Belgium | |
| X-PANDA,Progressive Metal,Estonia | |
| X-TG,Progressive Electronic,United Kingdom | |
| XAAL,RIO/Avant-Prog,France | |
| XADU,Jazz Rock/Fusion,Multi-National | |
| XALPH,Zeuhl,France | |
| XANADU,Heavy Prog,Poland | |
| XANG,Crossover Prog,France | |
| XANTHOCHROID,Tech/Extreme Prog Metal,United States | |
| XEN,Crossover Prog,United States | |
| XENN,Neo-Prog,Poland | |
| XENOGLYPH,Experimental/Post Metal,United States | |
| XENOGRAFT,Eclectic Prog,Australia | |
| XENOVERSE,Progressive Metal,Finland | |
| XERATH,Tech/Extreme Prog Metal,United Kingdom | |
| XERXES,Progressive Metal,Switzerland | |
| XFEARS,Progressive Metal,Brazil | |
| XHOHX,RIO/Avant-Prog,Belgium | |
| XHOL / EX XHOL CARAVAN,Krautrock,Germany | |
| XIBALBA,Progressive Metal,Slovakia | |
| XII ALFONSO,Symphonic Prog,France | |
| XINEMA,Crossover Prog,Sweden | |
| XING SA,Zeuhl,France | |
| XIU,Progressive Electronic,Italy | |
| XL,Eclectic Prog,Finland | |
| XMENOSUNO,Post Rock/Math rock,Mexico | |
| XNA,Symphonic Prog,United States | |
| BERNAR OLOTL,Progressive Electronic,France | |
| XOO,Psychedelic/Space Rock,United Kingdom | |
| XPRESSIVE,Progressive Metal,Poland | |
| XSAVIOR,Progressive Metal,Sweden | |
| XTRA,Jazz Rock/Fusion,Italy | |
| XYSTUS,Progressive Metal,Netherlands | |