Complex sentence: The Nightwatchman is the alter-ego and solo act of Rage Against the Machine, ex-Audioslave and Street Sweeper Social Club guitarist Tom Morello, which he created in 2003 as an outlet for his political views while playing non-political music with Audioslave.
Split into simpler sentences: The Nightwatchman is the alter-ego and solo act of Rage Against the Machine, Street Sweeper Social Club and former Audioslave guitarist Tom Morello. It was formed in 2003 as an outlet for his political views while he was playing music with Audioslave.