| 52879 | Sebastian Lizarraga | 1 | 1661 | 1661 |
| 48164 | Sebastian Ostolaza Kamio | 1 | 1648 | 1648 |
| 53227 | Sebastián Zubimendia | 1 | 1733 | 1733 |
| 53178 | Sebastiana Badilo | 1 | 1714 | 1714 |
| 51895 | Sebastiana Garagorri | 1 | 1769 | 1769 |
| 43551 | Secado Fuentes S.A | 1 | 1971 | 1971 |
| 42558 | Secundino Irazu Arregi | 1 | 1972 | 1972 |
| 43504 | Seguros La Estrella S.A | 1 | 1976 | 1976 |
| 42321 | Serapio Mujika | 1 | 1899 | 1899 |
| 43186 | Serapio Mujika Azkue | 1 | 1971 | 1971 |
| 53414 | Serverin Meravez | 1 | 1790 | 1790 |
| 53564 | Severa Jauregi | 1 | 1877 | 1877 |
| 53615 | Severo Jauregi | 1 | 1885 | 1885 |
| 42961 | Severo Narvarte | 1 | 1950 | 1950 |
| 52518 | Silvestre Amenabar | 1 | 1815 | 1815 |
| 47452 | Simon Eznarrizaga Unanberro | 1 | 1668 | 1668 |
| 53115 | Simón Irazoki | 1 | 1708 | 1708 |
| 52812 | Simón Lizolume | 2 | 1744 | 1745 |
| 52405 | Simon Ondarza | 6 | 1643 | 1739 |
| 51997 | Simon Sarobe | 1 | 1634 | 1634 |
| 52919 | Simón Sastorain | 1 | 1686 | 1686 |
| 52926 | Simón Sasturain | 1 | 1686 | 1686 |
| 42322 | Simon Ugalde | 1 | 1950 | 1950 |
| 52650 | Simona Aranburu | 1 | 1753 | 1753 |
| 43502 | Sociedad de Seguros Mutuos | 1 | 1975 | 1975 |
| 53698 | Sode S.A. | 4 | 1969 | 1976 |
| 43555 | Sorotxikiko bizilagunak | 1 | 1971 | 1971 |
| 42550 | Sucesores de Daniel Martinez | 1 | 1975 | 1975 |
| 42343 | Suministros para Fundición | 1 | 1974 | 1974 |
| 48242 | Talleres Aduna | 1 | 1955 | 1955 |
| 42342 | Talleres Biyona | 1 | 1974 | 1974 |
| 43416 | Talleres José Mª Elosegi Arregi | 1 | 1961 | 1961 |
| 43494 | Talleres Luis Mª Aya | 1 | 1966 | 1966 |
| 42392 | Talleres Vicuña S.A | 3 | 1965 | 1970 |
| 42462 | Telefonica S.A | 2 | 1971 | 1973 |
| 42514 | Teodoro Usandizaga Beobide | 2 | 1971 | 1972 |
| 52807 | Teresa Aialde | 1 | 1725 | 1725 |
| 52309 | Teresa Altuna | 1 | 1625 | 1625 |
| 52633 | Teresa Arralde | 1 | 1739 | 1739 |
| 52556 | Teresa Elgarresta | 1 | 1759 | 1759 |
| 52954 | Teresa Idiakez | 1 | 1694 | 1694 |
| 48280 | Teresa Mendibil | 1 | 1956 | 1956 |
| 53171 | Teresa Ugarte | 1 | 1714 | 1714 |
| 51740 | Teresa Urruzola | 3 | 1737 | 1739 |
| 52115 | Teresa Usobiaga | 1 | 1783 | 1783 |
| 52940 | Tiburcio Bergara | 1 | 1690 | 1690 |
| 53019 | Tolosako San Frantzisko komentua | 2 | 1699 | 1741 |
| 53085 | Tolosako Santa Klara komentua | 2 | 1692 | 1708 |
| 43089 | Tomar Arrastoa Iguaran | 1 | 1960 | 1960 |
| 52267 | Tomas Aialde Zulaika | 1 | 1659 | 1659 |
