Rock City, also known as R. City and Planet VI, is an American musical duo from Saint Thomas, U.S. Virgin Islands, formed in 2003. The duo, composed of brothers Theron and Timothy Thomas, who use the stage names, A.I. and Uptown AP respectively, are also a songwriting and record production team. The Thomas brothers also write and produce for other artists, including Jamaican artiste, Sean Kingston ("Take You There"), American singer, Miley Cyrus ("We Can't Stop"), Trinidadian rapper Nicki Minaj ("Only") and Barbadian popstar Rihanna ("Pour It Up").

The duo has also contributed to numerous Grammy-nominated albums including Rihanna's Unapologetic (which won Best Urban Contemporary Album), Jennifer Hudson's self-titled album (which won Best R&B Album), and Ariana Grande's My Everything (which was nominated for Best Pop Vocal Album).

Rock City also releases original music, having released several mixtapes since 2008. The group had previously been signed to Geffen Records and KonLive, where they released a series of mixtapes with the primary title, PTFAO (Put the F*ckin' Album Out)—a reference to the fact that their debut album Wake the Neighbors, had not been given a release date. In 2011, the duo was released from their contract with KonLive, and founded Rebelution Records, on which they intended to release their debut album. A new album, What Dreams Are Made Of, is due to be released in 2015, after being signed to Kemosabe Records and RCA Records by Dr. Luke.