Bill Fagan is a Distinguished University Professor in the Biology Department at the University of Maryland. He received an Honors B.A. from the University of Delaware (1992), a Ph.D. in Zoology from the University of Washington (1996), and was a postdoctoral fellow at the National Center for Ecological Analysis and Synthesis. His research, which emphasizes the interplay between data and theory, sits at the interface of mathematics and biology, where he has worked on a wide range of topics with many collaborators from diverse fields. An elected Fellow of both the Ecological Society of America and the American Association for the Advancement of Science, he also received a Guggenheim Fellowship and the Presidential Award of the American Society of Naturalists. Over his career, he has worked on a variety of projects in spatial ecology, quantitative conservation biology, and ecological stoichiometry (which focuses on the elemental balances underlying protein evolution, population growth, and species interactions). He has authored over 275 journal articles which have collectively garnered ~33,000 citations, and has twice had the cover of Science magazine for his research on animal movement ecology. Currently, his externally funded research focuses on mathematical investigations of migration and other long-distance animal movements, the role of phenology (biological timing) in species interactions, and the spread of disease. These projects have taken him around the world, including research on the steppes of Mongolia (studying the movement ecology of gazelles), the seasonally flooded Pantanal grasslands of Brazil (modeling the spatial ecology of armadillos and giant otters), and the icy coasts of Antarctica (studying the spatial distribution and population dynamics of penguins).