See:
- Ferdinand I of Castile and Leon (ca. 1000-1065, king from 1037)
- Ferdinand I of Aragon (1379-1416, king from 1412)
- Ferdinand I of Naples (ca. 1424-1494, king from 1458)
- Ferdinand I of Germany (1503-1564, emperor from 1556)
- Ferdinand I of the Two Sicilies (1751-1829, king of Naples from 1759)
- Ferdinand I of Austria (1793-1875, emperor from 1835)
- Ferdinand of Romania (1865-1927, king from 1914)
- Ferdinand of Bulgaria (1861-1948)