If there is one group that embodies progressive rock, it is King Crimson. Led by guitar/Mellotron virtuoso Robert Fripp, during its first five years of existence the band stretched both the language and structure of rock into realms of jazz and classical music, all the while avoiding pop and psychedelic sensibilities. The absence of mainstream compromises and the lack of an overt sense of humor ultimately doomed the group to nothing more than a large cult following, but made their albums among the most enduring and respectable of the prog rock era.