Where did it come from...?
Alexander is a surname originating in Scotland. It is originally an Anglicized form of the Scottish Gaelic MacAlasdair. It is a somewhat common Scottish name, and the region of Scotland where it traditionally is most commonly found is in the Highlands region of Scotland.
The first Alexander to America was Samuel Alexander (1657-1733). Excerpts from pages 14 , 15, and 18 of "EARLY ALEXANDERS AND CLOYD'S CREEK, BLOUNT COUNTY, TENNESSEE STATED:" Samuel Alexander was born in the North of Ireland, in 1657. He was one of seven Alexander brothers and two sisters that came to the Colony of Maryland from Derry, Ireland.
The Alexanders of Scotland and early American Colonists were Royal Descent of the Alexanders. The history of the family is brief. John (Macdonald), Lord of the Isles — Margaret (Princess of Scotland), daughter to Eobert II, King of Scotland. From this marriage are all the descended of the Alexanders.
This family line goes back to earlier times when they were Kings of Ireland, to Milesius Gallamh Of Spain (Father of the Irish Race), to Kings of Galicia, to the Kings of Scythia all the way to Japheth, son of Noah (the Ark). In Biblical tradition, Japheth is considered to be the progenitor of the European people. In medieval Europe various nations and ethnicities were given genealogies tracing back to Japheth and his descendants.