What is Gods of metal?

there are 4 of gods of metal
1)black sabbath
2)iron maiden
3)judas priest
4)slayer

black sabbath is 1st because black sabbath (ozzy)was the father of heavy metal followed by
iron maiden w/ bruces very high voice followed by
judas priest
then 10 - 15
years later slayer which saves heavy metal from dieing when gruge was taking over