Mother of Yaldabaoth and the form of Wisdom.
The mistakech. 4, 17
Chapter 17 ends by naming the demiurge outright: “Yaldabaoth: the ideal of imperfection, you were only ever a mother's mistake, Sophia's mistake; without father.” The sermons of chapter 4 say the Devil God “was cast into the outer darkness, of a Mother's mistake, unwanted and deformed; he could barely even remember.”
Wisdom of allch. 31
When Samson asks the hanging shadow who Wisdom of all is, Wisdom of Limbo answers: “Sophia is the mother of the devil-God Yaldabaoth, and she is the one who is the form of Wisdom.” He adds that Samson is closer to life in asking it.
Note: unofficially, Sophia comes from the Fullness.