In Bridgerton (both the books and the Netflix series), Sophie’s mother is an unnamed woman who worked as a maid and became the mistress of the Earl of Penwood, Lord Penwood, making Sophie his illegitimate daughter.

The story never gives her a specific name or detailed backstory; she is simply described as a maid (in some book references, even rumored as an actress), who died in childbirth, leaving Sophie to be raised first by her grandmother and then taken in as Lord Penwood’s ward.