Friendly-sounding name with big "Sweeney Todd" downside.

The double 'e' gives this Celtic surname a genial sound. It derives from an old Irish name — Suibhne (SHEEV-ne) that was borne by several early saints and kings, including, unfortunately, one known as Mad Sweeney who spent his life living in trees and composing nature poetry. Another possible drawback is the association with Sweeney Todd, the bloodthirsty butcher of Sondheim stage-musical fame.