Mrs. Hargreave (Victoria Horne; 1911-2003) and Mrs. Grimsby (Claire DuBrey; 1892-1993) are villainesses from 1949's Abbott and Costello Meet the Killer, Boris Karloff. They were part of a group of former clients of the film's murder victim, criminal attorney Amos Strickland.
Strickland was found murdered in his hotel room by bellboy Freddie Phillips (Lou Costello), with Angela Gordon, another client, appearing and expressing sorrow over his death. However, Angela later informed Mrs. Hargreave and Mrs. Grimsby, along with Swami Talpur, about the death, displaying a more cold demeanor. It was later revealed that the aforementioned women were conspirators in a plan to set up Freddie to take the fall, with the evil Mrs. Grimsby leading the charge.
The women, Talpur, and three other clients had learned that Strickland was retiring and writing a memoir, which could reveal the clients' secrets. Though Mrs. Grimsby and Mrs. Hargreave's secrets were never revealed, the duo continued their plan after client Mike Relia and Strickland's secretary Gregory Milford were both murdered, as they schemed to have Freddie take the fall for all three deaths. Mrs. Grimsby was shown scolding Angela for failing in her role, and she and Mrs. Hargreave (along with the rest of the group) went along with the Swami's plan to hypnotize Freddie into killing himself, which failed--ironically--due to Freddie's ineptness.
Though the villainesses did participate in the attempt to set up Freddie, it turned out that neither of them--nor any of the other clients--killed Strickland, who was revealed to have made up the story of retiring to draw out the clients. The killer was revealed to be hotel manager Milton, who was taken down and arrested. The fates of Mrs. Hargreave and Mrs. Grimsby were never revealed.