King Crimson is a pioneering British progressive rock band, formed in London in 1969. Known for their complex, genre-blending music, their style combines elements of jazz, classical, and experimental music with rock. The band, frequently led by guitarist Robert Fripp, has seen numerous lineup changes, with Fripp being the only constant member. Their debut album, "In the Court of the Crimson King," is regarded as a foundational and influential work in the progressive rock genre.