Charlotte AuerbachFRSFRSE (14 May 1899 - 17 March 1994), known by her friends as 'Lotte', was a German-Jewish zoologist and geneticist who contributed to founding the science of mutagenesis. She became well known after 1942 when she discovered with A. J. Clark and J. M. Robson that mustard gas could cause mutations in fruit flies. She wrote 91 scientific papers, and was a Fellow of the Royal Society of Edinburgh as of the Royal Society of London. In 1977, she was awarded the Royal Society's Darwin Medal. Aside her scientific contributions and love of science, she was remarkable in many other ways, including her wide interests, independence, modesty, and transparent honesty.