Mary E.P. Davis (1840-1924) was a nursing instructor and a founder of the American Journal of Nursing (AJN). Davis, along with Sophia Palmer, created AJN in 1899, with the first issue going out on October 1900. In order to create the journal, Davis reached out to 5,000 different people to subscribe to AJN and eventually started with 550 paid subscriptions. She also raised money for the journal and covered the mailing costs herself. Palmer and Davis also helped create the American Nursing Association. Davis was one of the founders of the American Society of Superintendents of Training Schools for Nurses which later became the National League for Nursing. She also served as the president of the Massachusetts State Nurses' Association.
Davis was appointed Superintendent of Nurses at the Boston Hospital for the Insane in 1901. Davis was a graduate of the Massachusetts General Hospital Training School, and a former student of Linda Richards. Davis also the held the position of superintendent of the University of Pennsylvania Hospital.
In 1982, she was inducted into the American Nurses Association Hall of Fame.