Sir Stephen Mackenzie FRCP[1] (14 October 1844 – 3 September 1909) was a British physician, knighted in 1903.
Mackenzie was a medical resident at the London Hospital and studied for a year at Aberdeen, where he became M.B.
After working in 1873 at the Charité Hospital connected with the University of Berlin, he returned to London in late 1873 and then spent the remainder of his career working as a physician at the London Hospital before retiring in 1905 due to health problems.
He also made some original observations on the distribution of the filarial parasites in the blood of man in relation to sleep and rest.
He employed glycerinated calf lymph for vaccination, thus reviving the practice instituted by Dr. Cheyne in 1853.