Good Things Come in Four's?
 

It seems as though each music movement has four main founding and influential bands... the most well known, and even referred to as "The Big-4 of Thrash," are Metallica, Megadeth, Slayer, and Anthrax.

But, I would also propose the following Big-4's

British Invasion (The Beatles, The Rolling Stones, The Who, The Kinks)
Prog (King Crimson, Yes, Genesis, ELP)
Punk (Ramones, Sex Pistols, The Clash, ????)
Neo-Prog (Marillion, IQ, Pendragon, Arena)
Grunge (Nirvana, Soundgarden, Alice In Chains, Peal Jam)

What other foursomes would you add, and anyone agree or disagree with the foursomes above?

Note: These are not necessarily my favorites in each genre (especially in the case of ELP), but I do think they are the founding fathers of their genres.

RMR