Since no one else has mentioned him yet, I’m going to tentatively recommend Keith Jarrett. His recordings with his group are more mainline jazz; the ones that impress me more, though, are his solo piano recordings. A lot of people tend to put these in with new age, but to me they are some of the most creative piano work I’ve ever heard. Try “The Koln Concert” first, and if you like that, go on to the others from there.
I’ll also recommend Sun Ra, but get yourself deeply rooted in jazz first before you take that step off the planet.
I’m not a big Sun Ra expert, but I DIG the Arkestra’s version of “Pink Elephant’s on Parade” from the “Stay Awake” CD (modern artists’ takes on songs from Disney films).
If you think that’s good, try to dig out an album called “Second Star to the Right.” (I think it’s currently only available as an import.) It’s a recording of a show they did in Austria right after “Stay Awake” came out of almost all Disney songs. Put’s a whole different spin on “Heigh Ho.” and “The Forest of No Return.”