If there is one group that embodies both the best and the worst aspects of progressive rock (from the standpoints of both supporters and detractors), it is King Crimson. During its first five years of existence from 1969 through 1974, in a variety of different lineups, this band led by guitar/Mellotron virtuoso Robert Fripp broke lots of new ground in prog rock, stretching both the language and structure of the music into realms of jazz and classical. Somehow, the group's challenging debut album, In the Court of the Crimson King, caught the public's collective ear at the right moment and hit number five in England.