'Thane' and, later of course, 'King'! Originally, he was Thane of Glamis and was then given the additional title, Thane of Cawdor befor murdering Duncan to become king.
Well I believe Mac means 'Son of', so he'd be 'Son of Beth'. Beth was one of the sisters in ''Little Women'' by Louisa May Allcott. Hope that helps. B.
An entertaining idea, Brionon, but Macbeth is not actually a patronymic - or even matronymic which your 'Beth' would suggest - surname. It is from the Gaelic for 'son of life'. It's an unusual concept, too, that a surname is the same as a title. But what the hey, eh?
There is some suggestion that Anson (Anne's son) and Nelson (Nell's son) might be matronymics. On the other hand, they might be 'Ian's son' and 'Neil's son' respectively.
Whatever... MacConcetta sounds a bit too Italian for my liking!
Wikipedia gives Beaton, Hilliard, and Megson as matronymics in English. Titles in other languages may become names, eg Chowdhury (like the recently dismissed Pakistani chief justice) and this chap in the paper yesterday: