There are multiple artists with this name:

1) Iron Maiden are an English heavy metal band formed in Leyton, east London, in 1975 by bassist and primary songwriter Steve Harris. The band's discography has grown to thirty-seven albums, including fifteen studio albums, eleven live albums, four EPs, and seven compilations.

Pioneers of the New Wave of British Heavy Metal, Iron Maiden achieved initial success during the early 1980s. After several line-up changes, the band went on to release a series of US and UK platinum and gold albums, including 1982's The Number of the Beast, 1983's Piece of Mind, 1984's Powerslave, 1985's live release Live After Death , 1986's Somewhere in Time and 1988's Seventh Son of a Seventh Son. Since the return of lead vocalist Bruce Dickinson and guitarist Adrian Smith in 1999, the band have undergone a resurgence in popularity, with their latest studio offering, The Final Frontier, peaking at No. 1 in 28 different countries and receiving widespread critical acclaim.

Despite little radio or television support, Iron Maiden are considered one of the most successful heavy metal bands in history, with The New York Times reporting in 2010 that they have sold over 85 million records worldwide. The band won the Ivor Novello Award for international achievement in 2002. As of October 2013, the band have played over 2000 live shows throughout their career. For the past 35 years, the band have been supported by their famous mascot, "Eddie", who has appeared on almost all of their album and single covers, as well as in their live shows.

The band has changed their line-up several times up to 1999 when Bruce Dickinson and Adrian Smith returned to the band.

Their current line-up is:

Steve Harris (1975-): bass, backing vocals, studio keyboards
David Michael Murray (1975-): guitar
Paul Bruce Dickinson (1981-1993 1999-): lead vocals (see also Bruce Dickinson, Samson)
Nicko McBrain (1983-): drums, percussion (see also Trust)
Janick Gers (1990-): guitar (see also Bruce Dickinson, White Spirit)
Adrian Smith (1980-1990, 1999-): guitar, backing vocals (see also Bruce Dickinson and Psycho Motel).

Former members:

Doug Sampson – drums, percussion (1977–1979)
Dennis Stratton – guitars, backing vocals (1979–1980)
Paul Di'Anno – lead vocals (1978–1981)
Clive Burr – drums, percussion (1979–1982)
Blaze Bayley – lead vocals (1994–1998)
Dennis Wilcock - lead vocals (1976–1977)
Barry Purkis – drums, percussion (1977)
Paul Day - lead vocals (1975–1976).

Iron Maiden's work has inspired other sub-genres of heavy metal, including power metal and speed metal, and is generally thought of as an influence to any "metal" music containing dual-guitar harmonization. One example of their far reaching influence is that many bands from virtually every rock and metal sub-genre list Iron Maiden as one of their influences.

Many of the band's songs are based on history, folklore, movies and books, such as Aces High, Brave New World, The Trooper, The Clansman, The Wicker Man, The Prisoner, Where Eagles Dare, Out of the Silent Planet, To Tame a Land(based on Frank Herbert's Dune) and Rime of the Ancient Mariner – in which words from the Samuel Taylor Coleridge poem are incorporated into the song.

http://www.ironmaiden.com/

2) Iron Maiden (later aka The Bolton Iron Maiden) is a late sixties doom-band. This Iron Maiden was formed in 1964 by Barry Skeels, Steve Drewett, Chris Rose and Alan Hooker as an acoustic band in Basildon, Essex that eventually evolved into a band called Iron Maiden. By 1966, the lineup was Skeels (bass), Drewett (vocals/harmonies), Rose (lead guitar), Tom Loates (rhythm guitar) and Stan Gillem (drums); they played Rolling Stones and blues numbers under the name "Growth". Reduced to a two-piece, Drewett and Skeels played blues under the name of "Stevenson's Blues Department" in pubs and clubs in Essex and London. They supported a number of up and coming bands including Jethro Tull, Fleetwood Mac, The Groundhogs and King Crimson.

In 1968, Drewett and Skeels were joined by Paul Reynolds (drums) and Trevor Thoms (guitar). They released an acetate (God of Darkness/Ballad of Martha Kent) under the then risqué name of BUM. When they signed to the Gemini label in 1970, the name was changed to the less risqué Iron Maiden. They recorded their debut album Maiden Voyage. Reynolds was replaced by Steve Chapman on drums and Iron Maiden released the single Ned Kelly/Falling. This coincided with Mick Jagger's film "Ned Kelly". A planned Australian tour fell through. The Gemini record label also folded (with the loss of the debut album master tapes) and Skeels left Iron Maiden. The band carried on without him for a while, but the debut album was not released until 1998 using duplicate tapes owned by Skeels. This "original" Iron Maiden is often considered by fans as one of the earliest 'true' doom metal bands.

However, soon after the "original" Iron Maiden was re-discovered , their name was officially changed to 'The Bolton Iron Maiden' since the Iron Maiden led by Steve Harris already had the name 'Iron Maiden' trademarked.

Somewhere Back in Time (The Best of 1980 - 1989)