Ernst L. Freud was an Austrian-born British architect and the fourth child of Austrian psychoanalyst Sigmund Freud and his German-born wife Martha Bernays. In honour of his wife, Ernst Freud added the initial L. to his name when he married in early 1920, making the middle initial stand for Lucie and not Ludwig as is often assumed.

Sigmund Freud was an Austrian neurologist and the founder of psychoanalysis, a clinical method for evaluating and treating pathologies seen as originating from conflicts in the psyche, through dialogue between patient and psychoanalyst, and the distinctive theory of mind and human agency derived from it.