Yao-Tzu Li or Y. T. Li (Chinese: 李耀滋; pinyin: Lǐ Yàozī; February 1, 1914, Beijing[1][2] – August 14, 2011[3]) was an American aerodynamicist, businessman, inventor, and mechanical engineer. He was the professor emeritus in aeronautics and astronautics at the Massachusetts Institute of Technology.