Nia Manning was a doctor with the Queens Borough Mental Institution.
Manning took over the treatment of Benny Russell from James Wykoff. Manning became Russell's friend, and tried to convince him to stop writing his Star Trek stories. She also gained Wykoff's permission to allow Russell to spend time outside in the grounds of the asylum. It was later revealed that Manning was being possessed by a Pah-wraith. (DS9 short story: "The Dreamer and the Dream")