What is iron best selling album?

Iron Maiden's best-selling album is "The Number of the Beast", released in 1982. It is the band's third studio album and is considered one of their most influential works. The album was a commercial success, reaching number one in the UK Albums Chart and number 15 on the US Billboard 200 chart. It has sold over 18 million copies worldwide, making it one of the best-selling heavy metal albums of all time.