Composed by George Frideric Handel.
The sarabande is a dance originating in Spain, but this particular sarabande has a peculiarly haunting quality, and was referenced in Joe Hisaishi's requiem for the 1984 film Nausicaä of the Valley of the Wind. It was also a staple of a cassette I listened to in bed as a kid, The Classical Child, vol. 1, where it was arranged in airy music-box-like synth tones by Ernest Mavrides.