Apparently recorded as McGivern, McGurn, Geran, Gerin, and Guerin, and probably others, this is an Irish surname. According to the famous Irish etymologist the last Edward MacLysaght, however spelt it may derive from the pre 10th century Gaelic or perhaps Manx name 'Mag Uidhrin' meaning 'The son of the dun coloured chief', and if so this may have been a name originally applied to a Viking. These Scandanavians occupied much of Ireland and the Isle of Man between the 8th and the 11th centuries, leaving their mark in many ways, not the least in names. However MacLysaght also implies that in some spellings it may be French Huguenot, and as such a 17th century settler name which has adopted a number of spellings. As a result one has to deduce that nobody really knows what the true origin is or whether each spelling is actually a different name with a different origin! From a research point of view the situation is made much worse in Ireland by the fact that most of the early church records were lost in 1922. This was when the IRA blew up the Public Records Office in Dublin.