John Venn is responsible or the origin of the well known Venn Diagram.It was so called Venn Diagram in honor of his name.Here's a little known speech by John Venn officially...
"I began at once somewhat more steady work on the subjects and books which I should have to lecture on. I now first hit upon the diagrammatical device of representing propositions by inclusive and exclusive circles. Of course the device was not new then, but it was so obviously representative of the way in which any one, who approached the subject from the mathematical side, would attempt to visualize propositions, that it was forced upon me almost at once."—John Venn
Click the picture below for the better view of his face.
Hope this Helps:)