The Old Woman, sometimes called the Mysterious Old Woman, is a minor but recurring character in the anime Paranoia Agent. She is a very short, homeless elderly woman with gray hair worn up and dark eyes. She keeps a makeshift shelter near the spot where Tsukiko Sagi is attacked by the assailant known as Lil' Slugger in the first episode, and she is a witness to that assault. Because her shelter is close to the scene of the first attack, she briefly becomes a minor figure of interest during the police investigation, though she is not involved in the crime itself. Her main significance in the story is as an observer of that central incident, which links her to the series' opening events.

She first appears when Tsukiko encounters her on the way home from work at the beginning of the story. She then disappears from the narrative for a period before returning in the fifth episode. In the sixth episode, her family connection is introduced when her granddaughter, Midori Shibazaki, comes to inquire about her. In this scene the old woman is shown speaking of her granddaughter's father's business, and she addresses her granddaughter as Midori-kun, which suggests a warm and familiar relationship between them. These later appearances connect her to a broader network of characters whose lives intersect with the Lil' Slugger phenomenon.

The series offers little direct information about her background, personality, or personal motivations, and she is presented mainly as an elderly woman living on the fringes of society rather than as a figure with a developed inner life. Her defining trait is observational: she is present at a crucial moment in the story, disappears for a time, and then resurfaces in connection with her granddaughter. She displays no special or supernatural abilities, and her role is defined by her proximity to the first attack and by her relationship with Midori Shibazaki.