Jacob Ludwig Karl Grimm, also known as Ludwig Karl, was a German author, linguist, philologist, jurist, and folklorist. He formulated Grimm's law of linguistics, and was the co-author of the Deutsches Wörterbuch, the author of Deutsche Mythologie, and the editor of Grimms' Fairy Tales. He was the older brother of Wilhelm Grimm; together, they were the literary duo known as the Brothers Grimm.
Jacob Gotfried Haafner was a German-Dutch travel writer who lived in and wrote extensively on India and Sri Lanka. His travelogues were noted for their Romantic undertones, lively descriptions of Indian cultures and peoples, as well as criticisms of European colonialism, slavery, and cultural domination.
Jacob Ilive was an English type-founder, printer and author. He was a religious radical, who developed neognostic views based on deism. He spent time in prison, convicted of blasphemy.
Jacob Klein was a Russian-American philosopher and interpreter of Plato, who worked extensively on the nature and historical origin of modern symbolic mathematics.
Jacob Leonard de Bruyn Kops, was a Dutch liberal economist, politician, and professor in political economy and administrative law at the Delft University of Technology.