Doctor Apollinaire was a 19th century Earth physician who worked at the San Francisco charity hospital known as Sisters of Hope Infirmary. He was one of the doctors who dealt with the cholera epidemic of the time, used as a cover by the Devidians so they could feed on Human neural energy.
As part of an investigation into the Devidians' activities, members of the USS Enterprise-D crew traveled to the past. Doctor Beverly Crusher posed as a nurse and worked at the Sisters of Hope Infirmary under Dr. Appollinaire. He was slightly contemptful of her suggested treatments. (TNG: "Time's Arrow, Part II")