I'll write the why for Rachmaninoff and thats about it. There is no song in the world more gut wrenching and utterly depressing and world ending as Rachmaninoff's Prelude in C# Minor. And no I'm not talking about the half ass version on the Shine soundtrack. I'm talking about the full version that speeds up in parts. David Helfgott does have a CD where he plays it but if you really look around you can find a copy of ol' Sergei playing it. The ingenuity of modern music is so vastly different from the early 1900's and this is a shining example of it. While we're getting lost in our technology or anti-technology styled musics, its good to add some study. There's nothing quite like Russian classical.
Rembrandt is up there, but I'd love to find out who actually did the Man with the Golden Helmet painting one day, it gave me goosebumps the first time I saw it, which is a feat when looking at art online I'd say. Then there's Titian Caravaggio Bermejo Mack Carlos Huante Marko Djurdjevic definitely seems to be takin a hold of the concept art industry
Shit, there are a ton I can't think of, but pretty much if I've heard of em, they've been influential.
hrmmm Joseph Vargo Zdzislaw Beksinski (god i hope i spelled that right) luis royo silvestri (doesn't really fit in with the others, but if I were to gain usage of my hands again for drawing and whatnot, my illustration style would be heavily influenced by him...) brom giger brian froud chad ward ashley wood ben templesmith
very inspiring people for me...i have a thing for dark, raw edged, energy filled painting...i also really like suydam's style and color usage sometimes...i have a moonknight zombie print he did all in orange, yellow and browns that i am really really fond of. I like rotty colors...:/
Probably lots of other people, but that's just off the top of my head as the most significant. I'd have to look through all my books and favorite websites and links and then the people I talk to...