I would have posted on the death of mathematician Benoit Mandelbrot on October 14 sooner, but my mother died on Oct. 8, and I have been completely absorbed with that until now (she is buried and all that).
Anyway, I think he was enormously important and deserved the Nobel Prize in economics. While one can see it implicit in not empirically sound work of Pareto in the 1890s and in Lotka and Zipf on city size distributions in the 1940s, it was Mandelbrot writing on cotton prices in the early 1960s who first recognized the phenomenon of fat tails in asset markets, which are ubiquitous in fact, and also linked these with the concept of fractals and fractal dimensionality, which has since become enormously influential and widespread across many disciplines, although the first fractal set was the Cantor Set, discovered by Georg Cantor in 1883.
I met Mandelbrot on several occasions and found him to be enormously impressive. He did have an enormous ego (and also the largest head I ever saw on anybody), but he was one of those people who had some grounds for his egotism. As most probably know, his career was very unconventional, and he was only offered an academic position when he was quite old (a special professorship at Yale), after he worked for many years at IBM.
In terms of current issues and debates, Mandelbrot was one of those along with Taleb who was warning for some time that we were likely to have a major crash of the financial system. More recently, John Cochrane invoked him in an effort to defend the Chicago School people from charges that their conventional financial market models that assume Gaussian normal distributions were partly responsible for the problems were not all that they believed. He pointed out that his father-in-law, Eugene Fama, had once been a follower of Mandelbrot, and therefore anyone who studied with Fama knew about fat tails, although Fama had fallen out with Mandelbrot over a technical issue (do variances vanish asymptotically; Fama was right that they do not but then dropped the ball by failing to notice that fourth moments, kurtosis, that is fat tails, do appear to vanish that way, making Mandelbrot right in the big picture).
Of course, when I went to look at Cochrane's big grad textbook, Asset Pricing, fat tails, kurtosis, and so on, much less fractals or power law distributions. do not appear in it at all. So, maybe Cochrane knew about fat tails, but he was not about to let anybody else know about them.
In any case, I think Mandelbrot was one of the few genuine geniuses writing about economics, although it was not his primary field of interest. His death is a great loss.