Not to be confused with Mary Black or Mary Thripp, two canonical characters of the novel
Mary is a non-canonical character created for the The Murder of Roger Ackroyd episode of Agatha Christie's Poirot, adapted from the novel with the same name. Mary is the parlourmaid of Mrs Dorothy Ferrars. Mary was only seen in one scene, talking to Inspector Davis about her employer's suicide.
She was portrayed by Alice Hart.