NECKHOLD tape on White Centipede (as mentioned).
NOVASAK (he doesn't always do harsh stuff, but he builds PAs to be louder than normal, and his own pedals, mixing boards, etc. Sometimes it is wall noise, but when he does harsh noise it is captivating).
Diaphragmatic (as mentioned).
Breakdancing Ronald Reagan (when he is not doing silly shit and sampling, it is excellent harsh noise of a hi-speed variety).
Architeuthis Dux - Acropolis CDr - Excellent movement, density, and texture. Not a dull moment in over 40 minutes, if I recall correctly.
I have seen AODL at least three times, and I wouldn't call it harsh noise, but I do enjoy it thoroughly. I don't remember any of his recording being what I'd call harsh noise.
XOME is still active and always mind-bogglingly good.
Vertonen, when he does a harsh set, is always good. It's sparing on his recordings, but the "Stations" CD hits on it most, as I recall. In Chicago, it has been very common that he play first and explode with deep bass and screaming distortion for 6 minutes or less.
Thirteen Hurts must play live with at least 30 pedals, and I usually roll my eyes at that, but he knows how to use them. Not always harsh in the way that we expect / want it, but dynamics and soundscapey territory with purely pedals, eventually punctuated with brutal harsh noise. This is a guy that only really plays noise fests. He lives in a geodesic solar powered dome in the middle of nowhere, Colorado, (6 hours from civilization in any direction, according to him) and he has driven to Florida to do a noise set. I've seen him 3 times, I have 2 of his CDs, and it is highly recommended.
Mutant Ape
Ascites
I know there are some I'm missing. I should say that Skin Graft isn't limited to harsh noise, but when he does it, it's extremely good.
I have to mention Kevin Shields (the noise act). She did an amazing escalating repetitive epic harsh noise set in 2010 that blew my mind. Her recordings are unable to match that performance, but still worth getting.
I hope Pope Joanna will continue at some point, but I can mention her here as she was on a split with PCRV in 2010. Could be my favorite harsh noise artist. Very sparing discography.
I don't mind "Crackle Studies" or certain "Wall Noise", but I really like "loop studies", and would like to see more of it.