- This article discusses close relatives of Judah. Er is also a name listed by the Gospel of Luke's version of the genealogy of Jesus.
In the biblical Book of Genesis, Er (Hebrew: עֵר, Modern Er Tiberian ʻĒr "awake; roused"; Greek: Ἤρ) was the eldest son of Judah and the daughter of Shuah, his Canaanite wife. He is described as marrying Tamar. According to the text, "the LORD slew" Er because he was wicked, although it does not give any further details. According to Rashi, he, like Onan, purposely tried to keep Tamar from conceiving, in his case because he was afraid of spoiling her beauty. Er had two brothers, Onan and Shelah.
According to biblical scholars, the description of Er is an eponymous aetiological myth concerning fluctuations in the constituency of the tribe of Judah, with the abrupt death of Er reflecting the death of a clan; the presence of an Er as a descendant of Shelah, in the Book of Chronicles, suggests that Er was in reality the name of a clan that was originally equal in status to the Shelah clan, but was later subsumed by it. The brother - Onan - may represent an Edomite clan named Onam, who are mentioned in an Edomite genealogy in Genesis.
Scholars have argued that the Tamar narrative, of which the description of Er is a part, secondarily aims to either assert the institution of levirate marriage, or present an aetiological myth for its origin; Er's role in the narrative would thus be as the background to the main plot, his death being the reason for levirite marriage to become an issue. John Emerton, Regius Professor of Hebrew at the University of Cambridge, regards the evidence for this as inconclusive, though classical rabbinical writers argued that this narrative concerns the origin of levirate marriage.