Mother of Mine

Mother/Wife of Mine was the matriarch of a criminal family called the Family of Blood. She resembled a gaseous entity prior to possessing a maid named Jenny.

She and her family tried to take the Tenth Doctor's life essence. When he caught her, to show her how horrible it was to live forever, she was thrown into the event horizon of a collapsing galaxy. (DW: Human Nature/The Family of Blood)