This page contains an index of all the surnames in the database. Selecting a link will lead to a list of individuals in the database with this same surname.
| Letter | Surname | Number of People |
|---|---|---|
| <absent> | 297 | |
| A | Ailello Thassaig | 1 |
| D | Dé Ní hEidin of Aidhne | 1 |
| E | Echdach | 1 |
| F | Fidaig | 1 |
| Finnegan | 1 | |
| H | Heber Donn | 2 |
| I | Ir Ulaid | 4 |
| K | Kelly | 6 |
| Kerrigan | 1 | |
| L | Lóegairi | 1 |
| Lugaid | 1 | |
| M | MacCarthy | 1 |
| Maccon | 1 | |
| MacDonnell | 1 | |
| MacMadagan | 1 | |
| Maguire | 40 | |
| Meadaib | 1 | |
| Míl Espáine | 1 | |
| Muiredach | 1 | |
| N | Néill | 12 |
| O | O'Brien | 1 |
| O'Canavan | 1 | |
| O'Carroll | 1 | |
| O'Daly | 1 | |
| O'Donnell | 6 | |
| O'Lavan | 1 | |
| O'Madagan | 1 | |
| O'Moran | 1 | |
| O'Neill | 13 | |
| O'Sullivan | 1 | |
| S | Sheridan | 1 |
| son of Bratha | 1 | |
| son of Cairbre | 1 | |
| son of Eochaidh | 5 | |
| son of Fionn | 1 | |
| son of Labhradh | 1 | |
| son of Sedna | 2 | |
| U | Ua Briain | 2 |
| Ua Conchobair | 9 |