Underground Sunshine was an American psychedelic rock band active during the late 1960s. The Wisconsin-based group comprised of brothers Bert and Frank Koelbl, along with Chris Connors and Jane Little. Notably, they achieved their greatest success with a cover of The Beatles' "Birthday," which reached number 26 on the Billboard Hot 100 in 1969. Their sound, a blend of garage rock and pop psychedelia, is emblematic of the era's music scene, but their career was short-lived, with only one album, "Let There Be Light," released in their active years.