Robert May died on April 28 at age 84 of unreported causes. He has been described as "the grandfather of chaos theory," which I think exaggerates, but he was the second person to adopt the term after James Yorke first applied to a porticular type of irregular nonlinear dynamics subject to the "butterfly effect" of sensitive dependence on initial conditions (butterfy effect having been coined by the late Edward Lorenz to climate modeld, a reason we cannot make weather forecasts beyond a week or so usually), well ahead of May's work. But May was one one of the most influential people working on chaos theory as well as many other important dynamical issues in a variety of disciplines, including ecology, medicine (he modeled pandemics), as well as economics and finance.
From Australia originally, he ended up in Britain where he served as Chief Science Adviser 1995-2000, which got him knighted in 1997, then made Baron of Oxford in 2000, and then an Order of Merit in 2001. He has been pretty much universally admired, and his work has long been influential on mine as well as on that of many others, even predating my interest in chaos theory when I read his work on dynamics in ecosystems, which has been highly influential and original.
Probably his most famous paper, in which he was the first to suggest that chaos theory might be applicable to economics, along with many other disciplines, was "Simple mathematical models with very complicated dynamics," Nature, 1976, 261, 471-477. May he rest in peace.