Betsy Ancker-Johnson (April 29, 1927 – July 2, 2020) was an American plasma physicist. She was known for her research into instabilities that can occur in plasmas in solids, and for her invention of a gigacycle range signal generator using semiconductor materials in magnetic and electric fields. She was the first woman Presidential appointee in the U.S. Department of Commerce. She is the fourth woman elected to the National Academy of Engineering.