Jean Alexandre Dieudonné was a French mathematician, one of the most prominent members of the group Bourbaki. He helped Grothendieck in writing EGA and, together with Laurent Schwartz, advised Grothendieck in his early (pre-thesis) research in analysis. Apart from Bourbaki activities, Dieudonné was prolific in expository writing, having a rare “photographic” memory and high working habits (writing steadily at least 5 pages per day in the best period), immense erudition and strong attitude on all topics. Comparatively he was much less productive in original research - however most important is his development of the study of (Cartier-)Dieudonné modules arising in theory of formal groups. There is a theorem in general topology having his name.
Most important books (except for large portion of Bourbaki’s “Elements”)