The Essential Iron Maiden by Iron Maiden (CD, Jul-2005, 2 Discs, Legacy Recordings)

27 tracks and I still need more. Where are Remember Tomorrow, Children of the Damned, and Hallowed Be Thy Name "the Live After Death version" How about Where Eagles Dare, Powerslave and Dance of the Dead. Thats just my opinion of what essential Maiden is, but this cd set will certainly do fine.

Spanning Iron Maiden's career up until 2005's 'Death on the Road' live album this album serves as a great introduction to the band's music. It has a formulaic approach which actually works quite well - reverse chronological order (of the original release of the song if not necessarily the version presented) and selecting (mainly) two tracks from each album.
I have minor quibbles about track selection - the omission of 'Hallowed be thy Name', the overemphasis at times on singles, etc. But the fact is that any track selection is going to be contentious on a full length double CD, and in the main this is a very well balanced compilation with a good cross section of above standard tracks which are almost ideal for the intended audience (non-Iron Maiden fans). But I suspect that the people who actually buy the album will be established fans...

Compilation released only to the USA, is not really part of the official discography of Maiden, but essential to a collector.