Namesakes
Fictional Characters from Books:
1 character
Niall Brigant 2001 The Southern Vampire Mysteries 
Fictional Characters from Television:
1 character
Niall Brigant 2008 True Blood
Irish Kings:
4 kings
King Niall Noígíallach 368-395
King Niall Frossach 763-770
King Niall Caille 833-846
King Niall Glúndub 916-919
Notable Actors and Entertainers:
1 actor, 1 actor/comedian
Niall Tóibín 1929-2019
Niall Matter 1980-
Notable Athletes:
1 cricket, 1 soccer
(cricket) Niall O'Brien 1981-
(soccer) Niall McGinn 1987-
Notable Musicians:
1 singer
Niall Horan 1993-