John Venn, a British logician. And, consequently, it is the Venn diagram, not the venn diagram.
John Venn
John Venn!
John Venn.
venn diagram
Venn diagrams are named after their inventor, John Venn.
John Venn
Venn diagrams were conceived around 1880 by John Venn.
John Venn published a work in 1880 with his venn diagrams.
john venn
He used them in his studies of logic.
hE invEnTed THe vEnn DiaGrAm ,,