Marcus Manuel Hartog was an English natural historian and educator in Cork, Ireland. He contributed to multiple volumes of the Cambridge Natural History.

Hartog was born in 1851, the second son of the Professor Alphonse Hartog (d.1904) and Marion (née Moss) (1821-1907), younger brother of Numa Edward Hartog

Numa Edward Hartog

Numa Edward Hartog was the brother of Marcus Hartog and Philip Hartog. Although he died young, he is notable for having been the first Jewish Senior Wrangler at Cambridge University, in 1869. He also won 2nd Smith's Prize in that year.In his earlier academic career, he attended University...

 and elder brother of Sir Philip Joseph Hartog, Academic Registrar of London University and Vice-Chancellor of the University of Dacca. Hartog was educated at the North London Collegiate School, University College, London, and Trinity College, Cambridge, where he took a first class in the National Science Tripos in 1874, and then went out in the same year to Ceylon as assistant to the Director of the Royal Botanic Gardens there — a post that he held for three years. On his return he became demonstrator, and afterwards lecturer, in natural history at Owens College, Manchester, and in 1882 he began an association of more than 40 years with the educational life of Cork. For 27 years he was Professor of Natural History in Queen's College, Cork (1882-1907). there and in 1909 he proceeded to the chair of Zoology in University College, Cork. When in 1921 he vacated the appointment, Dr. Hartog was made Emeritus Professor.Professor Marcus Hartog died in Paris on 21 January 1924.

In 1874 in Paris, France, he married Blanche Levy, daughter of R. Levy, of Paris, and had issue.

Hartog contributed articles to the Dictionary of National Biography

Dictionary of National Biography

The Dictionary of National Biography is a standard work of reference on notable figures from British history, published from 1885...

and the Encyclopaedia Britannica as well as writing many articles for scientific journals.