|Played by||Briana Cuoco|
|First Appearance||Lydia Bennet!: Episode 1: Boredom|
|Cousins||Jane Bennet, Lizzie Bennet, Lydia Bennet|
Mary is a somber, sensible girl who is often seen reading, and she will sometimes play piano...though she isn't good at it according to Lydia. Mary will often wear black clothing and wear her black hair down, following the stereotype of a goth or emo(Lydia refers to Mary as an emo).
In episode 26, Mrs. Bennet forces her 3 daughters out of her house for remodeling, and while Jane Bennet and Lizzie Bennet go to Bing Lee's house in Netherfield, Lydia Bennet is not invited, so she goes to her cousin Mary's house. Lydia and Mary at first do not get along, but as time passes, Mary and Lydia grow closer. They eventually begin to call each other friends and they start hanging out on a regular basis.
After Jane moves to Los Angeles, and Lizzie goes to Collins and Collins, Lydia once more visits with Mary. Lydia then proceeds to ditch Mary for Jane, causing Mary to get mad at her again. Lydia and Mary then proceed to reform their friendship, until Lydia once again returns home.
Mary makes a small appearance in The Lizzie Bennet Diaries during Lydia's 21st birthday.