William Orlando Markham (1818-1891) was an English physician and pioneer of cardiology.

After education at Edinburgh, Paris, and Heidelberg, William Markham graduated in 1840 M.D. in the University of Edinburgh, where he obtained a gold medal for his thesis on the surgical practice of Paris, illustrated by cases. He became house-surgeon to the York Road Lying-in Hospital and soon after was appointed physician to the Blenheim Street Dispensary. He resigned that position when he was elected to