Supersister was a Dutch band from The Hague, Netherlands, playing progressive rock ranging from jazz to pop. The most predominant band members were Robert Jan Stips (keyboards, vocals), Sacha van Geest (flute), Marco Vrolijk (drums) and Ron van Eck (bass).

The band started as Sweet OK Sister in 1968 as a school band with singer and songwriter Rob Douw, who soon thereafter left. The remaining members continued as a more serious musical quartet under the name Supersister. Their style was progressive rock (in Canterbury Scene style) in which Stips' keyboard play played a dominant role.