John Fenn, American chemist and academic, Nobel Prize laureate (d. 2010)
John Bennett Fenn (June 15, 1917 – December 10, 2010) was an American professor of analytical chemistry who was awarded a share of the Nobel Prize in Chemistry in 2002. Fenn shared half of the award with Koichi Tanaka for their work in mass spectrometry. The other half of the 2002 award went to Kurt Wüthrich. Fenn's contributions specifically related to the development of electrospray ionization, now a commonly used technique for large molecules and routine liquid chromatography-tandem mass spectrometry. Early in his career, Fenn did research in the field of jet propulsion at Project SQUID, and focused on molecular beam studies. Fenn finished his career with more than 100 publications, including one book.

Fenn was born in New York City, and moved to Kentucky with his family during the Great Depression. Fenn did his undergraduate work at Berea College, and received his Ph.D. from Yale. He worked in industry at Monsanto and at private research labs before moving to academic posts including Yale and Virginia Commonwealth University.Fenn's research into electrospray ionization found him at the center of a legal dispute with Yale University. He lost the lawsuit, after it was determined that he misled the university about the potential usefulness of the technology. Yale was awarded $500,000 in legal fees and $545,000 in damages. The decision pleased the university, but provoked mixed responses from some people affiliated with the institution, who were disappointed with the treatment of a Nobel Prize winner with such a long history at the school.