Lostprophets /lɒstˈprɒfɪts/ were a Welsh rock band from Pontypridd, formed in 1997. Founded by their lead vocalist Ian Watkins, bassist (later guitarist) Mike Lewis, drummer Mike Chiplin and guitarist Lee Gaze, they were originally a side-project to hardcore punk band Public Disturbance. Lostprophets released five studio albums, with their final release Weapons being released on 2 April 2012. They were also part of the Cardiff music scene. The band achieved two top ten hits on the UK Singles Chart ("Last Train Home" and "Rooftops"), one number one single on the Alternative Songs chart ("Last Train Home"), several Kerrang! Awards and nominations, and sold around 3.5 million albums worldwide.

In late 2012, Watkins was charged with multiple sexual offences against children. The band cancelled all tour dates and their future remained uncertain until the other members announced the disbanding of Lostprophets in October 2013 before the end of the trial. Watkins pleaded guilty to several (but not all) charges in November 2013, and in December 2013 was sentenced to 29 years imprisonment plus six years on licence.