Poti-Phera
Poti-phera is an Egyptian priest of On, named in the Joseph cycle as the father of Asenath and therefore Joseph's father-in-law. He appears only in connection with that marriage and the children it produced; no speech, action, or further biography is recorded for him.
Priest of On
The marriage and the priestly identification are tied together in a single notice. When Pharaoh elevates Joseph and gives him an Egyptian name, he also gives him a wife: "And Pharaoh called Joseph's name Zaphenath-paneah; and he gave him as wife Asenath, the daughter of Poti-phera priest of On" (Gen 41:45). On is the city; the priesthood is the office; the marriage seals Joseph's standing inside Pharaoh's court.
Father of Asenath, Grandfather of Manasseh and Ephraim
The line through Asenath produces Joseph's two sons, born in Egypt before the famine years. "And to Joseph were born two sons before the year of famine came, whom Asenath, the daughter of Potiphera priest of On, bore to him" (Gen 41:50). The genealogy in Genesis 46 makes the same identification when it lists the descendants who came into Egypt: "And to Joseph in the land of Egypt were born Manasseh and Ephraim, whom Asenath, the daughter of Poti-phera priest of On, bore to him" (Gen 46:20). Through Asenath, then, Poti-phera's line carries into the tribal structure of Israel: Manasseh and Ephraim are his grandsons.
The spelling alternates between Poti-phera (Gen 41:45; 46:20) and Potiphera (Gen 41:50) within the same context. The office and the city — priest of On — are constant.