Ei-ichi Negishi (born July 14, 1935) is a Japanese chemist who has spent most of his career at Purdue University, United States. He is best known for his discovery of the Negishi coupling. He was awarded the 2010 Nobel Prize in Chemistry "for palladium catalyzed cross couplings in organic synthesis" jointly with Richard F. Heck and Akira Suzuki.

He graduated from the University of Tokyo in 1958, and did his internship at Teijin. He went to study in the United States and obtained his PhD from University of Pennsylvania in 1963 under the supervision of professor Allan R. Day. In 1966, He became a postdoc researcher at Purdue University, and became assistant professor in 1968, working with Nobel laureate Herbert C. Brown. In 1972, he went to become assistant professor at Syracuse University. In 1979, he was promoted to professor at Syracuse University. In the same year, he went back to Purdue University.
In 2000 he was awarded the Royal Society of Chemistry's Sir Edward Frankland Prize Lectureship.