Blue Sunday is a tender ballad written by Jim Morrison for The Doors' 1970 album Morrison Hotel. The composition emerged from Morrison's habit of singing blues numbers during informal, often inebriated jam sessions with the band during their formative period in the mid-1960s, making it one of the earliest pieces in The Doors' catalog despite its later release. The song is characterized by its striking emotional contrast: the instrumental backdrop carries a somber, dirge-like quality, while the lyrics express an earnest, optimistic plea of romantic devotion. Morrison delivers the vocal in a soft, crooning baritone style reminiscent of Frank Sinatra, with careful enunciation and understated passion that stands apart from the more intense vocal approach he employed on much of The Doors' material. The harmonic foundation is a simple blues-based progression, and the arrangement is deliberately spare and intimate, with responsive drumming and subdued instrumental accompaniment that emphasize emotional vulnerability over musical complexity. On Morrison Hotel, the piece follows directly from the hard-driving "Peace Frog," creating a dramatic shift in mood that heightens the impact of both compositions. At under two minutes, Blue Sunday functions as a brief, poetic interlude within the album's sequence, showcasing a gentler, more reflective dimension of Morrison's artistry that contrasted with his reputation for chaos and provocation.