... The French Colin is probably Nicolas, and is the parent of all the Arcadian Colins who piped to their shepherdesses either in the rural theatricals of the ancient regime, in Chelsea china, or in pastoral poetry...
... Though often confounded with the Scottish Colin, it is perhaps the French form that has the best right to the feminine invention of Colinette. (History of Christian Names, Yonge, 1884)

COLIN.  Scottish form of Latin Columba (q.v.), meaning "dove."  Also spelled Collin.  Usage: America, Australia, England, Great Britain, Ireland, Scotland, Wales.
    Colin Firth, a British actor.  Colin Jackson, a Welsh hurdler.  Colin McAllister, a Scottish interior designer and television presenter. (Wiki)

McCallen.  The son or descendants of Callen or Colin.  This name was given to the descendants of Sir Colin Campbell, or Colin the Great, who flourished toward the end of the thirteenth century, at Lochore, Scotland. (An Etymological Dictionary of Family and Christian Names, Arthur, 1857).

... The Scottish Colin may, perhaps, have been slightly influenced by French taste, but he bears no relation to Nicolas, being, in fact, formed from the Irish missionary, Saint Columba (Columb)...
... Colin, so frequent among the Scots of all ranks, is the direct descendant of Columba, though it is often confounded with the French Colin, from Nicolas... (History of Christian Names, Yonge, 1884)