Yongbin Ruan (Chinese: 阮勇斌; pinyin: Ruǎn Yǒngbīn; born 14 February 1963) is a Chinese mathematician, specializing in algebraic geometry, differential geometry, and symplectic geometry with applications to string theory. He has been a visiting professor at the ETH Zurich, in Hong Kong, and at MIT. He was in 1993 and again in 2004 at the Institut des hautes études scientifiques, in 1993 at the Max Planck Institute for Mathematics, in 1994 at Cambridge's Isaac Newton Institute, and in 1994 at the Mathematical Sciences Research Institute.