English, derived from the Roman name Marcus, itself possibly derived [Whyte] from Mars, the Roman God of War; NT Gospel of St Mark.

As Martin is also derived from Mars, we classify Martin and Mark as lesser synonyms.

Note: ONC states that the origin of Marcus is "unknown".

Although both are rare, Marcus and Mark occur as often as each other in the 1841 Census of Aberdeenshire.

In old documents in Latin, Marcus was used, with appropriate case endings, for Mark.