Israel Jacob Kligler (24 April 1888 – 23 September 1944) was a microbiologist. A Zionist and humanist, he was born in the Austro-Hungarian Empire, educated in the United States and spent most of his career in Mandatory Palestine, but died before the creation of the State of Israel. He was one of the first four professors of the Hebrew University and the founder of Department of Hygiene and Bacteriology of the university, which he headed until his death in 1944. Kligler was one of the pioneers of modern medical research in Mandatory Palestine, studying as varied a field as Bacteriology, Parasitology, Virology, Nutrition, Epidemiology and Public Health. He developed the Kligler Iron Agar medium for the isolation and identification of intestinal bacteria, which is still in use today.