Fernández
Patronymic surname, derived from Fernán or Fernando, (from Ferrandus), broadly distributed throughout the Iberian Peninsula. Just like other patronymic surnames, different families with this name are not related.
In the beginning, Fernández and Hernández surnames were confused as being the same name. As result, many historic characters are named Fernández or Hernández depending on the text you are reading. That is what happens with the great captain Gonzalo Fernández de Córdoba. Searching an encyclopedia for this character you can find a "see also Hernández de Córdoba" note. It is hard to split the two surnames and find the origin of Hernández. Both surnames have their origin in the name Ferrán, which means "devoted warrior / fervent warrior". Derived from the word "Har" translated as war and power.
Starting with Ferrán o Hernán, derived names are Fernando / Fernández and Hernando / Hernández. In catalan the name remains in the original Ferrán, translated as Fernando in spanish. It is also possible that the surname Fernández (or Hernández) were adopted by the king Fernando.
Many of these proved nobelty in different occasions, under several Military orders and Real Chancelleries of Valladolid and Granada.
Surname origin by province:
Navarra: from Espronceda village, Estella district. The second navarra house of this surname stablished in Longuida village, Aois district.
Vizcaya: centred in Álava, spreading in several branches: Fernández or Hernández de Iruela, Fernández or Hernández de Beraza, Fernández or Hernández de Leiva, Fernández or Hernández de Ubago, Fernández or Hernández de Vicuña, Fernández or Hernández de Soro.
Asturias: this surname had its oldest appearance in Asturias near Covadonga. De él salieron numerosas ramas, extendidas por toda la provincia. De la Cangas de Onís, salieron la de Ronderos (Teverga), la de Lena y la de Navía. Otras aparecieron en Grado, Camuño (Salas), Otur (Luanca), Gijón, Allande, Belmonte, Tineo, Granda (Siero). De éste última, salió a su vez, la de Candamo.
Aragón: these families are derived from the ones from Navarra.
Castilla: The oldest family in Soria, centred in the villages of Yanguas and Ágreda. Rodrigo Hernández or Fernández was the founder of these, he was called "El Justador", possibly because of the many tournaments he was in. He moved from La Rioja to Castilla with Carlos de Arellano, Lord of Cameros.
Galicia: Strongly bound to the family in Vizcaya with the same name. Almost evry galician branch has Basoue origin. Fernández or Hernández de Gincio, from Vilamea (Lugo), and Fernández or Hernández de Soro.
Murcia: The only Fernández or Hernández family in the kingdom of Murcia and was the starting point for the others, started in Fuente Alama village, Cartagena district.
Andalucía: The ancient records reveals that Fernández or Hernández is related with an old knight from the kingdom of Córdoba.