Dirk Polder (23 August 1919 – 18 March 2001) was a Dutch physicist working on solid-state physics, magnetism, molecular physics and nanoscale physics.
Together with Hendrik Casimir, Polder first predicted the existence of what today is known as the Casimir-Polder force, sometimes also referred to as the Casimir effect or Casimir force. Using a similar theory, he developed the formalism to treat radiative heat transfer at the nanoscale.