| English Surname | Original Irish Surname Male | Original Irish Surname Female Unmarried | Original Irish Surname Female Married |
| Yago | Iagó | Iagó | Iagó |
| Yannahan | Ó hAnnacháin | Ní hAnnacháin | Uí hAnnacháin |
| Yeats | de Gheata | de Gheata | de Gheata |
| York(e) | Mac Conchearca | Nic Conchearca | Mhic Conchearca |
| Young | de Siún, Ó hÓgáin | de Siún, Ní hÓgáin | de Siún, Uí hÓgáin |
| Yourell | de Oirghialla | de Oirghialla | de Oirghialla |
Y
