Fritz Geiser is a zoologist who is interested in the comparative and environmental physiology of animals. He works mainly on the ecological physiology and biochemistry of mammals and birds, especially with regard to hibernation and daily torpor and has published over 220 papers on these and related topics. 

Fritz received his undergraduate degree in biology from the University of Hohenheim, Stuttgart, and a PhD from Flinders University, Adelaide. He has held postdoctoral positions at the University of Washington, Seattle, and the University of Adelaide. Fritz has worked in Zoology at the University of New England in Armidale since 1988 but, during this time, has conducted projects in Argentina, Austria, Canada, China, Germany, South Africa and the USA. He has been an Alexander von Humboldt Fellow, President of the Australian Mammal Society and an ARC Discovery Outstanding Researcher Award (DORA) Fellow. Currently, Fritz is Professor of Zoology and Director of the Centre of Excellence for Behavioural and Physiological Ecology.