Mrs. William Elliot is a character mentioned in Persuasion. She died half a year before the course of the novel, and thus did not make any appearances. She was an heiress and married William Elliot, the heir presumptive of Sir Walter Elliot, a baronet. She left him with a fortune when she died.
Although her family was wealthy, they did not have a good bloodline. She was not even a gentlewoman; her father was a grazier, and her grandfather was a butcher. Despite this, she was a fine woman and had a decent education. William married her solely for her money, so she was trapped in a loveless marriage before her death.