Monsters and Robots is Buckethead's fifth studio album, released April 20, 1999, by Higher Octave records. A large part of the album was co-written with Les Claypool, who also plays bass on several tracks and lends his vocals to the track «The Ballad of Buckethead».Buckethead promoted the album by opening for Primus in October and November 1999. Monsters and Robots is listed in the German National Library's catalog and is Buckethead's best selling solo album to date.