- May 17 Lydia Estes Pinklham, patent-medicine manufacturer, dies
- May 20 William Chambers, Scottish author and publisher (Basis of Communication & Coding), dies at 83
- May 23 Cyprian Norwid, Polish painter, poet and playwright (Wanda), dies at 61
- May 24 Abdel Kadir, Algerian leader (b. 1808)
- May 26 Abdelkader El Djezairi, Algerian leader, scholar and national hero (b.1808)
- May 26 Edward Sabine, Irish astronomer (b. 1788)
- May 28 August Freyer, composer, dies at 79
- May 29 Albrecht of Prussia, mistress of John van Rossum, dies at 73
- May 29 WFLC Marianne, princess of Orange-Nassau, dies