I'm kind of shocked that this already hasn't been mentioned, but the the great contemporary American composer died on November 5th at the age of 103.
2 time Pulitzer Prize winner for his 2nd and 3rd string quartets, he continued to compose until shortly before he died. He composed more than 40 works between 90-100 and another 14 after he turned 100. Some great pieces, too.
He was a great one, as far as I'm concerned. But then, I am a huge fan of 20th century, contemporary and avant-garde classical, so he was a major figure in my world.