For this Niall Brendan there are 5 different names on Yasni.
In the ranking of the most common first names Niall Brendan is on position 4586.
Male first name (Irish); (?) Niall master; Old Irish (Word format); niall = the master; from the Gaelic name 'Niall', whose meaning is disputed, perhaps a 'master'
Male first name (English, Irish); (?) Brendan Prince, Old Irish (Word format); from the Latinized form 'Brendanus' of an old Irish name 'Bréanainn', perhaps with the meaning 'Prince', known by the Saint. Brendan, a famous Irish monk (6th century)