Kōichirō Nishikawa

Kōichirō Nishikawa (, born 1949 - November 28, 2018) was a Japanese elementary particle physicist, known for contributions to neutrino physics. He was professor emeritus of the KEK high-energy physics laboratory and Kyōto University.

Nishikawa graduated from Kyōto University in 1971 and completed his doctorate at Northwestern in 1980 working with . After working at the University of Chicago, State University of New York, and Tōkyō University, he combined positions at KEK and Kyōto University, eventually becoming director of the Institute for Particle and Nuclear physics at the KEK laboratory and deputy director of the J-PARC proton accelerator facility.

In 2016, Nishikawa and the K2K and T2K groups received the Breakthrough Prize in Fundamental Physics together with other neutrino research collaborations. He was awarded the Nishina Memorial Prize in 2005, and the Bruno Pontecorvo Prize in 2016. He also received the 1998 Asahi Prize as part of the Super-Kamiokande experiment that discovered the mass of neutrinos.