| artist,genre,country | |
| J'ACCUSE..!,Crossover Prog,Italy | |
| J. A. CAESAR,Psychedelic/Space Rock,Japan | |
| J.E.T.,Rock Progressivo Italiano,Italy | |
| J.R.B SYMPHONY,Progressive Metal,Spain | |
| J21,Crossover Prog,Spain | |
| JACK DUPON,RIO/Avant-Prog,France | |
| JACK O' THE CLOCK,Prog Folk,United States | |
| JACK YELLO,Heavy Prog,Germany | |
| JACKAL,Heavy Prog,Canada | |
| JACKO WACKO,Psychedelic/Space Rock,Peru | |
| JACKS,Psychedelic/Space Rock,Japan | |
| JACKSON HEIGHTS,Prog Related,United Kingdom | |
| AND ACKSON,Psychedelic/Space Rock,United Kingdom | |
| RONALD SHANNO ACKSON,Jazz Rock/Fusion,United States | |
| JACULA,Rock Progressivo Italiano,Italy | |
| JADE,Psychedelic/Space Rock,France | |
| JADE WARRIOR,Psychedelic/Space Rock,United Kingdom | |
| JADIS,Neo-Prog,United Kingdom | |
| JAÉN KIEF,Crossover Prog,Colombia | |
| JAGA JAZZIST,Jazz Rock/Fusion,Norway | |
| JAHRTAL,Prog Folk,Austria | |
| LO AIVAS,Prog Folk,Chile | |
| JAKEL,Experimental/Post Metal,Canada | |
| JAKOB,Post Rock/Math rock,New Zealand | |
| JAKKO M AKSZYK,Canterbury Scene,United Kingdom | |
| JALAYAN,Psychedelic/Space Rock,Italy | |
| JAM CAMP,Jazz Rock/Fusion,United States | |
| JAM IT!,Jazz Rock/Fusion,Russia | |
| JAMBINAI,Post Rock/Math rock,Korea | |
| JAN DUKES DE GREY,Prog Folk,United Kingdom | |
| JANA DRAKA,Crossover Prog,Italy | |
| JANE,Heavy Prog,Germany | |
| JANISON EDGE,Neo-Prog,United Kingdom | |
| JANOS VÁRGA PROJECT,Eclectic Prog,Hungary | |
| BER ANSCH,Prog Related,United Kingdom | |
| BENN ANSSON,Jazz Rock/Fusion,Sweden | |
| JANUS,Rock Progressivo Italiano,Italy | |
| JANUS,Crossover Prog,United Kingdom | |
| JANVS,Experimental/Post Metal,Italy | |
| JAPAN,Prog Related,United Kingdom | |
| JAPANSKI PREMIJERI,Eclectic Prog,Croatia | |
| JARDÍN DE LA CROIX,Post Rock/Math rock,Spain | |
| JARDIN DE PIEDRA,Heavy Prog,Peru | |
| JARGON,Crossover Prog,Greece | |
| JARKA,Jazz Rock/Fusion,Spain | |
| JEAN-MICHE ARRE,Prog Related,France | |
| JÄRVET,Crossover Prog,Finland | |
| RO ARZOMBEK,Tech/Extreme Prog Metal,United States | |
| JASPER WRATH,Crossover Prog,United States | |
| JASTREB,Psychedelic/Space Rock,Croatia | |
| JAUGERNAUT (A.D.),Crossover Prog,United States | |
| CATHERIN AUNIAUX,RIO/Avant-Prog,Belgium | |
| JAZ,Crossover Prog,France | |
| JAZZ PISTOLS,Jazz Rock/Fusion,Germany | |
| JAZZ Q,Jazz Rock/Fusion,Czech Republic | |
| JAZZCOMPUTER.ORG,Progressive Electronic,France | |
| JB FAIRFIELD,Crossover Prog,Australia | |
| JEAN LOUIS,RIO/Avant-Prog,France | |
| JEAVESTONE,Eclectic Prog,Finland | |
| JEBEL,Crossover Prog,United States | |
| JED,Prog Folk,United States | |
| JEFFERSON AIRPLANE,Proto-Prog,United States | |
| JEJE GUITARADDICT,Progressive Metal,Indonesia | |
| JELLY FICHE,Symphonic Prog,Canada | |
| TH ELLY JAM,Psychedelic/Space Rock,United States | |
| JENGHIZ KHAN,Heavy Prog,Belgium | |
| JENIFEREVER,Post Rock/Math rock,Sweden | |
| IAI ENNINGS,Neo-Prog,United Kingdom | |
| JENZEITS,Progressive Electronic,United States | |
| JEREMY,Crossover Prog,United States | |
| JEREMY IRONS AND THE RATGANG MALIBUS,Crossover Prog,Sweden | |
| JERONIMO,Krautrock,Germany | |
| JERSEYBAND,RIO/Avant-Prog,United States | |
| JESDAT,Progressive Electronic,Spain | |
| JESETER,Neo-Prog,Czech Republic | |
| JESTER,Crossover Prog,United States | |
| JESTER,Prog Folk,United Kingdom | |
| JESTER'S JOKE,Rock Progressivo Italiano,Italy | |
| JESTER'S MARCH,Tech/Extreme Prog Metal,Germany | |
| TH ESTERDAYS,Prog Folk,Greece | |
| JESU,Experimental/Post Metal,United Kingdom | |
| JESUS WITH ME,Psychedelic/Space Rock,United States | |
| JET BLACK SEA,Crossover Prog,Netherlands | |
| JET LAG,Rock Progressivo Italiano,Italy | |
| JETHRO TULL,Prog Folk,United Kingdom | |
| JETHZABEL,Progressive Metal,Ecuador | |
| JEWY SABATAY,Experimental/Post Metal,Serbia | |
| JHIMM,Crossover Prog,United States | |
| JIHEL,Progressive Electronic,France | |
| JIMI SUMÉN PROJEKT,RIO/Avant-Prog,Finland | |
| JIMMY CHAMBERLIN COMPLEX,Heavy Prog,United States | |
| JIMMY YOKO & SHIN,Jazz Rock/Fusion,Japan | |
| GEORG INDA,Jazz Rock/Fusion,Hungary | |
| JINETE AZUL,Jazz Rock/Fusion,Argentina | |
| JINETES NEGROS,Progressive Metal,Argentina | |
| JINJER,Tech/Extreme Prog Metal,Ukraine | |
| GUSTAV OBIM,Progressive Electronic,Brazil | |
| EDDI OBSON,Progressive Electronic,United Kingdom | |
| JODY GRIND,Crossover Prog,United Kingdom | |
| TH OE K-PLAN,Post Rock/Math rock,Spain | |
| BJÖR OHANSSON,Symphonic Prog,Sweden | |
| JEN OHANSSON,Jazz Rock/Fusion,Sweden | |
| JOHN FRUM,Tech/Extreme Prog Metal,United States | |
| JOHNNY BOB,Neo-Prog,Germany | |
| JOHNNYTWENTYTHREE,Post Rock/Math rock,United States | |
| ALPHONS OHNSON,Jazz Rock/Fusion,United States | |
| SCOT OHNSON,RIO/Avant-Prog,United States | |
| JOIN IN,Jazz Rock/Fusion,Germany | |
| JOLLY,Neo-Prog,United States | |
| JON & VANGELIS,Prog Related,United Kingdom | |
| JON OLIVA'S PAIN,Progressive Metal,United States | |
| FRYDERY ONA,Progressive Electronic,Germany | |
| JONAS MUNK & NICKLAS SŘRENSEN,Progressive Electronic,Denmark | |
| JONATHAN,Progressive Electronic,Germany | |
| JOHN PAU ONES,Heavy Prog,United Kingdom | |
| NIGEL MAZLY ONES,Prog Folk,United Kingdom | |
| JONESY,Heavy Prog,United Kingdom | |
| JONO,Crossover Prog,Sweden | |
| JONO EL GRANDE ,RIO/Avant-Prog,Norway | |
| LARS ONSSON,RIO/Avant-Prog,Sweden | |
| JORDSJŘ,Symphonic Prog,Norway | |
| JORK,RIO/Avant-Prog,Ireland | |
| JORM,Crossover Prog,Sweden | |
| JOSEPH MAGAZINE,Progressive Metal,Poland | |
| BRYA OSH,Prog Related,United Kingdom | |
| JOUIS,Crossover Prog,United Kingdom | |
| JOURNAL,Tech/Extreme Prog Metal,United States | |
| JOURNEY,Prog Related,United States | |
| JOVENABUELO,Post Rock/Math rock,Chile | |
| JOVIAC,Heavy Prog,Finland | |
| JOX,Prog Folk,France | |
| JOY HEIGHTS,Psychedelic/Space Rock,Japan | |
| JOY UNLIMITED,Eclectic Prog,Germany | |
| JOY WANTS ETERNITY,Post Rock/Math rock,United States | |
| JÜ,Jazz Rock/Fusion,Hungary | |
| JUAN S. GARCÉS,Progressive Metal,Ecuador | |
| JUD'S GALLERY,Krautrock,Germany | |
| JUGGERNAUT,Experimental/Post Metal,Italy | |
| JUGLANS REGIA,Heavy Prog,Italy | |
| JAKO UHKAM,RIO/Avant-Prog,Estonia | |
| JUKE,Psychedelic/Space Rock,France | |
| JULIAN'S TREATMENT,Eclectic Prog,United Kingdom | |
| JULIE'S HAIRCUT,Psychedelic/Space Rock,Italy | |
| JULIA ULIEN,Jazz Rock/Fusion,France | |
| JULVERNE,RIO/Avant-Prog,Belgium | |
| JUMBO,Rock Progressivo Italiano,Italy | |
| JUMP,Neo-Prog,United Kingdom | |
| JUMP FOR JOY!,RIO/Avant-Prog,Multi-National | |
| JUNE CLEAVER AND THE STEAK KNIVES,Eclectic Prog,United States | |
| JUNE OF 44,Post Rock/Math rock,United States | |
| JUNEGRASS,Krautrock,United States | |
| JUNG PEOPLE,Post Rock/Math rock,Canada | |
| JUNGLE,RIO/Avant-Prog,Japan | |
| JUNIPHER GREENE,Heavy Prog,Norway | |
| JUNIUS,Post Rock/Math rock,United States | |
| JUNK FARM,Heavy Prog,Germany | |
| JUNON / EX GENERAL LEE,Experimental/Post Metal,France | |
| JUPITER HOLLOW,Progressive Metal,Canada | |
| JUPITER SOCIETY,Progressive Metal,Sweden | |
| JUPU GROUP,Jazz Rock/Fusion,Finland | |
| JUS PRIMAE NOCTIS,Rock Progressivo Italiano,Italy | |
| JUSTINE,RIO/Avant-Prog,Canada | |
| JUSTINE,Prog Folk,United Kingdom | |
| JUTRO,Jazz Rock/Fusion,Yugoslavia | |
| JUUDAS ISKARIOTIN SUUDELMA,Psychedelic/Space Rock,Finland | |