Denis Gascoigne Lillie (27 August 1884 – 13 May 1963) was a British biologist who participated in the "Terra Nova" Expedition (1910–1913) to the Antarctic. He collected numerous marine animals as well as plants and fossils–many of which were new to science–and published scientific papers on whales, fossils, and medicine. He received the Polar Medal along with other "Terra Nova" members in 1913. He was also a noted caricaturist who made cartoons of professors, colleagues, and friends: some of his caricatures are collected in the National Portrait Gallery. He worked as a government bacteriologist during World War I and then suffered a severe mental breakdown, spending three years at Bethlem Royal Hospital and never fully recovering. He is commemorated in the names of several marine organisms as well as Lillie Glacier in Antarctica.