Brendan m. Welsh breenhin 'a prince'.
The name of two 6th C Irish saints.
Despite its Welsh etymology, the name is actually Gaelic in origin, a borrowing of the Welsh word in the form Brénainn (Old and Middle Irish) or Bréanainn (Early Modern Irish). The spelling Brendan, common in English contexts, developed from the Latinization Brendanus or Brandanus.