Growing the Beard: At the start of their recording career, the band released two albums with Paul Di'Anno on vocals. While the opinion of these varies wildly among fans, it was the release of The Number of the Beast, combined with the introduction of Bruce Dickinson to form their most well-known lineup, that really propelled them into notoriety.
Never Live It Down: Back in 1982, Maiden put out a little song called "The Number of the Beast". To this day, many people still think they're evil Satanists.
Poor Man's Substitute: The band apparently wanted Vincent Price to record the haunting spoken word intro to the title track, but later refused when he asked for a fee of £25,000, turning to the much less expensive Barry Clayton instead (they even asked him to perform in a Price impression). This isn't such a bad thing, since fans always lose their minds when the intro plays in concert.
Replacement Scrappy: Averted with Dickinson: he's almost universally regarded as even better than his predecessor Paul Di'Anno.
Signature Song: "Run to the Hills" or "The Number of the Beast" are both considered big contenders.
Ditto for "Hallowed Be Thy Name".
The Woobie: You can't help but feel awful for the poor narrator of "Hallowed Be Thy Name".