Iron Maiden's third disc, The Number of the Beast, is where the group found their voice. Literally. Before they began recording the 1982 classic, they booted singer Paul Di'Anno in favor of Bruce Dickinson. Kicking out the frontman is a risky move for any band, but when fans heard Dickinson's incredible, operatic range, they were sold. This is not a band with a lot of hit songs, but The Number of the Beast's "Run To The Hills" and the title track did actually get some airplay. More importantly, the album doesn't have a single weak moment, from the opening notes of "Invaders" to the end of "Hallowed Be Thy Name." The group only grew in popularity from here, but they never quite reached this level of sheer perfection.