Planet X is an evolution of keyboardist Derek Sherinian's 1999 solo album Planet X. Sherinian has stated in several interviews that his intention when forming Planet X was to create a band that "played their instruments so fiercely, that they would strike fear in the hearts of all musicians". Sherinian has called the band's style "metal fusion".

There is more than one artist with this name: 1) Planet X are an American progressive fusion band. The core members are Derek Sherinian on keyboards and Virgil Donati on drums. Tony Macalpine was featured on the first two studio albums, but has recently left the band. Brett Garsed and Allan Holdsworth are featured on the latest Planet X album as guest musicians. The bass duties have been handled by various players live and in the studio, but they finally officialized Rufus Philpot as an official