The Manx (Isle of Man) surname Crain, also found in Scotland and Ireland is of patronymic origin being derived from the Gaelic name Mac Ciarain meaning "the son of little Keiran."in the 14th century. The Clan originated in Country Donegal and was brought to the Isle of Man and Scotland in medieval times. The first written reference occurs in 1408 when 1177 when John McCroyn in the "Manx Nae Register." John Crain aged 32 yrs., immigrated to Mobile County, Alabama in 1844. Today there are approximately 18,000 bearers of the name Crain living in the United States.