Onan

Onan was the second son of Judah by the Canaanite woman Bath-shua, and the brother of Er (Genesis 38:4, 8–10). After his elder brother Er died childless and under divine judgment, Onan was required by levirate custom to take Er's widow Tamar and produce an heir for his brother's line. Onan deliberately frustrated this obligation, and God put him to death as well (Genesis 38:9–10). His action gave the term 'onanism' its traditional meaning in moral theology, though the precise nature of his offense and its primary moral category—whether the violation of levirate duty or the specific act—has been debated.