Mercury Rev is an American rock band formed in 1989 in Buffalo, New York, with singer/guitarist Jonathan Donahue and guitarist/clarinetist/sound generator operator Sean "Grasshopper" Mackowiak as the only constant members. The band's music has incorporated indie rock, psychedelic rock and American roots, amongst other forms. Mercury Rev have been closely associated with The Flaming Lips, and the two bands have shared historical ties.

Grasshopper is an American musician with the band Mercury Rev. He has also appeared with Rev side-project Harmony Rockets, his own band Grasshopper and the Golden Crickets, and as a guest musician on numerous other recordings.