King Crimson have three titles in Rolling Stone magazine’s 50 Greatest Prog Albums Of All Time list. In reverse order:
No.20

With his third lineup in four years, King Crimson guitar maestro Robert Fripp finally tapped back into a musical energy as powerful and groundbreaking as that of his 1969 debut In the Court of the Crimson King. The group's fifth album was a masterful mélange of painstaking composition and wild experimentation, as if Fripp were depicting a madman struck with glimmers of melancholy clarity. In the end, it's difficult to tell which passages were happy accidents and which were carefully constructed; and it's even harder to determine which are more impactful, as clattering trays, chiming bells, twittering birds, understated voices and clown-toy laughter intertwine with tinny, static-filled guitar, epileptic beats and violin lines that range from gorgeous to harrowing. J.W.
No.15

Like most of their fellow prog-rockers, King Crimson began as a crew of English pastoral fantasia-slingers, though more schizoid than most. By Red, with the Sixties little more than a bad hangover, guitar guru Robert Fripp had distilled his approach down to a trio playing the most bone-crunchingly heavy music prog had yet heard. The sound of his serrated guitar abstractions slashing through Bill Bruford's beat jungles and John Wetton's low-end theorizing defined the idea of a power trio, and it's not hard to imagine, per legend, that Kurt Cobain dug this record and took notes. Ultimately, the intensity imploded; Fripp broke up the band soon thereafter, following a spiritual path, before reforming it with Bruford years later. But it was never as powerful as this. W.H.
No.2

One of the most influential progressive rock albums of all time, King Crimson's debut eschewed the bluesy bluster of late-Sixties British rock for a Mellotron-drenched mixture of jazz and classical influences, dragging psychedelia to a darker place than it had ever been before. "King Crimson will probably be condemned by some for pompousness," wrote Rolling Stone's John Morthland at the time, "but that criticism isn't really valid. They have combined aspects of many musical forms to create a surreal work of force and originality." With guitarist Robert Fripp and multi-instrumentalist Ian McDonald piling on layers of majestic sound, and bassist Greg Lake intoning evocative and foreboding lyrics, tracks like the unrelenting opener "21st Century Schizoid Man," the haunting "Epitaph" and the stately closer "The Court of the Crimson King" set the tone and template for the coming prog revolution. DE
You can read the full list here.
No.20

With his third lineup in four years, King Crimson guitar maestro Robert Fripp finally tapped back into a musical energy as powerful and groundbreaking as that of his 1969 debut In the Court of the Crimson King. The group's fifth album was a masterful mélange of painstaking composition and wild experimentation, as if Fripp were depicting a madman struck with glimmers of melancholy clarity. In the end, it's difficult to tell which passages were happy accidents and which were carefully constructed; and it's even harder to determine which are more impactful, as clattering trays, chiming bells, twittering birds, understated voices and clown-toy laughter intertwine with tinny, static-filled guitar, epileptic beats and violin lines that range from gorgeous to harrowing. J.W.
No.15

Like most of their fellow prog-rockers, King Crimson began as a crew of English pastoral fantasia-slingers, though more schizoid than most. By Red, with the Sixties little more than a bad hangover, guitar guru Robert Fripp had distilled his approach down to a trio playing the most bone-crunchingly heavy music prog had yet heard. The sound of his serrated guitar abstractions slashing through Bill Bruford's beat jungles and John Wetton's low-end theorizing defined the idea of a power trio, and it's not hard to imagine, per legend, that Kurt Cobain dug this record and took notes. Ultimately, the intensity imploded; Fripp broke up the band soon thereafter, following a spiritual path, before reforming it with Bruford years later. But it was never as powerful as this. W.H.
No.2

One of the most influential progressive rock albums of all time, King Crimson's debut eschewed the bluesy bluster of late-Sixties British rock for a Mellotron-drenched mixture of jazz and classical influences, dragging psychedelia to a darker place than it had ever been before. "King Crimson will probably be condemned by some for pompousness," wrote Rolling Stone's John Morthland at the time, "but that criticism isn't really valid. They have combined aspects of many musical forms to create a surreal work of force and originality." With guitarist Robert Fripp and multi-instrumentalist Ian McDonald piling on layers of majestic sound, and bassist Greg Lake intoning evocative and foreboding lyrics, tracks like the unrelenting opener "21st Century Schizoid Man," the haunting "Epitaph" and the stately closer "The Court of the Crimson King" set the tone and template for the coming prog revolution. DE
You can read the full list here.