According to the Book of Genesis, Dan (Hebrew: דָּן, Standard Dan Tiberian Dān; "judgment" or "he judged") was the fifth son of Jacob with Bilhah. He was Bilhah's first son. He was the founder of the Israelite Tribe of Dan. In the biblical account, Dan's mother is described as Rachel's handmaid, who becomes one of Jacob's wives. (Genesis 30:1-6)
According to the Book of Jubilees, Dan was born on the 9th of Elul.
The text of the Torah explains that the name of Dan derives from dananni, meaning he has judged me, in reference to Rachel's belief that she had gained a child as the result of a judgment from God.
Owing to the Book of Judges, in the account of Micah's Idol, describing the tribe of Dan as having used ephod and teraphim in worship, and Samson (a member of the tribe of Dan) being described as failing to adhere to the rules of a Nazarite, classical rabbinical writers concluded that Dan was very much a black sheep; in the Book of Jeremiah, the north of Canaan is associated with darkness and evil, and so rabbinical sources treated Dan as the archetype of wickedness. In the apocryphal Testaments of the Patriarchs, Dan is portrayed as having hated Joseph, and having been the one that invented the idea of deceiving Jacob by the smearing of Joseph's coat with the blood of a kid; in the apocryphal Prayer of Asenath, Dan is portrayed as plotting with the Egyptian crown prince, against Joseph and Asenath. In the Blessing of Jacob, Dan is described as a serpent, which seems to have been interpreted as connecting Dan to Belial, a connection made, for example, in the apocryphal Testament of Dan; early Christian writers, such as Irenaeus and Hippolytus, even believed that the Antichrist would come from the tribe of Dan drawing the belief from a verse from the Book of Jeremiah which states the snorting of [the enemy's] horses was heard from Dan.
John the apostle omits the tribe of Dan when mentioning the 12 tribes of the sons of Israel, in regard to the 144,000 sealed Israelites. Perhaps this is a testimony of the unworthiness of Dan. Instead of Dan, the tribe of Joseph appears twice.