I think that the albums below are the best for a beginner metal fan.
So, my list (without Thrash, Power, Glam etc)
Accept -- Breaker (or Metal Heart, or Balls To The Wall)
Iron Maiden - Somewhere In Time
Judas Prist - British Steel or Painkiller (but it's more Power-Metal disk)
Saxon - Wheels Of Steel
Manowar - Kings Of Metal
Iron Maiden - Seventh Son...
Iron Maiden - Killers
Dio - Holy Diver
U.D.O. - Animal House
Warlock - Burning The Witches