Light -- M John Harrison
Light is a novel about three individuals slowly calcifying into crushing, existential pain and meaninglessness. Their only hope is an unknown force that lurks in the wild of the Kefahuchi Tract, a reality-defying and endlessly pillaged reliquary in space home to the detritus of a trillion exhausted civilizations. A change that obliterates: but also one that saves? Light is SF as existentialism, and while sometimes indulgent, I'd count it among one of my favorite books.