ORIGIN OF THE CAMPBELL NAME CURVED MOUTH
Diarmid Campbell of Scotland says CAMPBELL comes from Gaelic cam buel (curved mouth) [others have said crooked or bent mouth] These are but one of three popular themes.

DE CAMPO BELLO
John Keltie, in his Notes, refers to an unsubstantiated Knight named de Campo Bello who supposedly came to England with William the Conqueror. Go See John Keltie's Notes Alistair Campbell of Airds, in his book "A History of Clan Campbell, Volume 1 From Origins to Flodden" mentions this theory. However, Alistair says that "all the early charters spell the name Cambel, and the 'p' does not appear until the fifteenth century

CAMBUS BELLUS
I have also found reference to the first Campbell being Archibald, the son of Malcom MacDuibhn (the second) and Cambus Bellus Beauchamp who married in Normandy. I cannot verify that this is true. It appears common in those days that if the mother was royal or otherwise significant, the child sometimes takes some form of the mother's name. They came to Scotland where Archibald Campbell married Eva O'Dwin, thus starting the long CAMPBELL clan. Eva was the daughter of Paul A Soporren MacDuibhn. - -