what are the heavy metal bands?

Heavy Metal is a genre of rock music which developed in the late 60s and early 70s. The bands that created heavy metal developed a thick, heavy, guitar-and-drums-centered sound, which was highly amplified and often featured fast guitar solos. It is an extreme form of rock music with its roots in blues-rock and psychedelic rock. Followers of this genre of music were known as 'metalheads' or 'headbangers', and early heavy metal bands included Led Zeppelin, Black Sabbath and Deep Purple. These bands attracted large audiences. Lots more heavy metal bands followed, some of the more popular ones being Judas Priest, Guns'N'Roses, Black Sabbath, Slayer, Motorhead, Morbid Angel, Iron Maiden, Opeth, Moonspell and Metallica, to name but a few.

Brightest Blessings.

You can not really define Heavy Metal bands unless you are talking about the very begining of the "Metal Movement." Judas Priest could be considered a part of the New Wave Of British Heavy Metal, instead of plain heavy metal. I would say the majority of Metal bands would fall in more then one category for different people.