Merzbow is the moniker of Japanese noise artist Masami Akita.
The name is taken from a work by Kurt Schwitters called "Merzbau,"
which was basically a room filled up with random junk (or found art, if you will).
This gives you a pretty good idea of what the music is like...
a thunderous maelstrom of digital and analogue noise, heavily distorted samples,
complete chaos yet at the same time meticulously structured.
I see it as punk rock stripped completely bare until only the most visceral and intense elements are left,
other people see it as aural torture. In either case, it's a lot of fun.
If you're interested in exploring his VAST back catalogue,
a good place to start is Merzbeat since the noise is at least looped and has a beat.
Aqua Necromancer similarly is based off of old prog-rock drum beats (not that you'll really be able to discern them, but oh well).
1930 is considered by many his masterpiece, and it is pretty mind-melting.