De Morgan or de Morgan is a surname, and may refer to:

  • Augustus De Morgan (1806–1871), British mathematician and logician
  • De Morgan's laws (or De Morgan's theorem), a set of rules from propositional logic
  • The De Morgan Medal, a triennial mathematics prize awarded by the London Mathematical Society
  • Campbell De Morgan (1811–1876), British surgeon
  • William De Morgan (1839–1917), English designer, potter, ceramics-worker, and novelist
  • Mary De Morgan (1850–1907), English author of literary fairytales
  • Evelyn De Morgan (1855–1919), English pre-Raphaelite painter
  • Jacques de Morgan (1857–1924), French archaeologist

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