(Montague) David Eder (1 August 1865 – 30 March 1936) was a British psychoanalyst, physician, Zionist and writer of Lithuanian Jewish descent.

Following the completion of his studies, he travelled through the United States, South Africa, Colombia (where he visited his uncle James Martin Eder), and Bolivia, where he became a non-commissioned military surgeon for the Bolivian Army.

He would later recall the physical and mental injuries suffered by the frontline troops in his 1917 book War-Shock, The Psycho-neuroses in War: Psychology and Treatment.

His influence stretched beyond medical circles: the novelist D. H. Lawrence alluded to Eder's pamphlet The State Endowment of Motherhood in the book The White Peacock.

Writing in the British Journal of Medical Psychology, Eder argued that while civilization is moving forward due to advances in science, politics and technology, these advances are actually contributing to greater unhappiness as man perceives a loss of control over his environment.