King-Wai Yau (Chinese: 游景威; pinyin: Yóu Jǐngwēi; born October 27, 1948) is a Chinese-born American neuroscientist and Professor of Neuroscience at Johns Hopkins University School of Medicine in Baltimore, Maryland.

in physics (University Scholar; Phi Beta Kappa) from Princeton in 1971 and a Ph.D. in neurobiology from Harvard in 1975, completing his doctoral thesis under John G. Nicholls, a former student of Bernard Katz.

In 1986, he became Professor of Neuroscience and Investigator of Howard Hughes Medical Institute (1986-2004) at Johns Hopkins University School of Medicine, where he has been since.

He has greatly elucidated the properties of the light responses and their underlying phototransduction mechanisms in retinal rods and cones,[1] as well as in intrinsically-photosensitive retinal ganglion cells which express the photopigment, melanopsin, to mediate mostly non-image vision such as pupillary light reflex and photoentrainment of the circadian rhythm.

His investigations on the spontaneous activity of rod and cone pigments have provided a physicochemical explanation for why our vision does not extend into Infrared wavelengths.