From the Hebrew name יִצְחָק (Yitzchaq) which meant "he laughs". Isaac in the Old Testament was the son of Abraham and the father of Esau and Jacob. As recounted in Genesis, God tested Abraham's faith by ordering him to sacrifice his son, though an angel prevented the act at the last moment.

As an English Christian name, Isaac was occasionally used during the Middle Ages, though it was more common among Jews. It became more widespread after the Protestant Reformation. Famous bearers include the physicist and mathematician Sir Isaac Newton (1643-1727) and the science-fiction writer Isaac Asimov (1920-1992).