On the Prowl is the ninth studio album released by the Japanese heavy metal band Loudness. It is also their second and last album with American vocalist Michael Vescera, before he left to join Yngwie Malmsteen's band. On the Prowl is mainly a compilation of self-covers of songs from early Loudness' albums, containing only three new songs written by the band. However, Mike Vescera translated and adapted the lyrics of the old songs written by former vocalist Minoru Niihara, to be sung in English.