Walter Gilbert (born March 21, 1932) is an American physicist, biochemist, molecular biology pioneer, and Nobel laureate.

Gilbert was educated at the Sidwell Friends School, Harvard University and the University of Cambridge where he did his PhD thesis under another nobel laureate Abdus Salam.

In 1979, Gilbert was awarded the Louisa Gross Horwitz Prize from Columbia University together with Frederick Sanger. In the following year, he was awarded the 1980 Nobel Prize in Chemistry with Frederick Sanger and Paul Berg.
Gilbert first proposed introns and exons and explained the evolution of introns in a seminal 1978 "News and Views" paper published in Nature. In 1986, Gilbert proposed the RNA world hypothesis for the origin of life.