Issachar or Yissachar (יִשָּׂשׁכָר "Reward; recompense", Standard Hebrew Yissaḫar, Tiberian Hebrew Yiśśâḵār) was the fifth son of Jacob and his first wife Leah. According to Genesis, Issachar was conceived on the night that Leah tried to use mandrakes brought to her by her oldest son Reuben to remedy her infertility. Because Leah took her child's birth to mean that she was divinely favored, she gave him the name Issachar.

As the ancestor of the tribe of Israel bearing his name, Issachar and his people settled in the Jezreel Valley and the low hills east of Mount Tabor. Jacob's blessing, given in Egypt and recorded in Genesis 49, describes Issachar as "a strong ass" who "became a slave at forced labor", perhaps indicating that the tribe of Issachar was one subject to the Canaanites of that region.

Issachar fathered four sons who joined him in the migration of Jacob's family to Egypt, where he died and was buried. Among his descendants were the judge Tola and two kings of Israel, Baasha and his son Elah.