Pharaoh, the adoptive Grandfather of Moses, was an unnamed individual who served as the ruler over Egypt after Joseph died. He is mentioned early in the book of Exodus, and he is not Moses' biological grandfather, but took him in as a result of his daughter taking him as her own son.
In the Bible, it is noted that this Pharaoh did not know Joseph, and showed obvious fear of the Hebrews, who had by this time grown numerous. Such fears were based on the idea that they would side with any army other than theirs, and help destroy Egypt. He directed that heavy burdens on them be placed upon them, but though the Israelites were struggling, they still multiplied. Angry and fearful, he planned to set back the Israelites by having all of the newborn sons killed by the Hebrew midwives, but this plan failed as the midwives feared God more than they feared him. As a result, he commands that every Israelite newborn should be cast into the Nile, something that leads to baby Moses' discovery by his daughter. Later, he seeks to kill Moses when Moses comes to the aid of an Hebrew being beaten by an Egyptian.
After his death, the Pharaoh who Moses consults to try and free the Israelites comes to power.