Shiing-Shen Chern, one of the great geometers of the twentieth century, died last Friday at Nankai University. He was 93 years old. An article about his life is posted on the web-site of MSRI, the mathematics institute in Berkeley of which he was the founding director.
A lot of what I know about geometry was learned from his beautiful short book entitled “Complex Manifolds Without Potential Theory”, published by Springer in 1979. Some of his most important work concerned the topology and geometry of fiber bundles, and its significance can be seen in the number of crucial ideas of this field that carry his name, for instance: Chern classes, the Chern character, Chern-Weil theory, the Chern-Simons secondary characteristic class.
Update: The New York Times has an obituary.