Van Halen has always been known as more of a "Party Rock" band than Metal, but their style, larger-than-life persona, massive arena shows, and of course Eddie's guitar was a very influential force on Heavy Metal.  Thousands of kids picked up the guitar because of Eddie, he was right behind Jimi Hendrix as far as influential and exciting players.

One can't forget Alex Van Halen either, his double-kicks were like thunder and soon every kid was playing faster and faster trying to replicate his style.  Alex easily hold's his own with any Metal band out there, and most of them would admit to playing along to Van Halen and studying his style.

Van Halen's live shows were even heavier and faster than the albums.  Here's "Unchained" from 1981.