The site’s full name is Generador de Nombres de Fantasía. Enjoy. 🙂
Full disclosure: while Portuguese is my native tongue and I’ve been fluent in English since my teens, Spanish (or “castellano“, if you prefer) isn’t something I’m fluent in. It’s similar enough to Portuguese (after all, Portugal and Spain share the Iberian Peninsula, and the two cultures have a lot in common) that I can understand it, especially in written form; I remember as a teen reading Micro Hobby, a Spanish video game magazine, and had no problems understanding it.
However, understanding a language — or being understood by a native — is very different from actually being able to write in the language, especially if you don’t want your text to scream “foreigner!”. As of now, I started out with online translators (both Google and Bing’s, which give slightly different results), then I corrected obvious errors, and, for terms I had doubts about, I looked for them the Spanish Wikipedia, to make sure that the translation made sense. Still, I’m pretty sure a native will find something wrong with it. 🙂 If you’re one and do so, I’d appreciate a comment. 🙂
As a bonus, it can generate modern Spanish / hispanic names, too. No super-heroes / villains, so far… maybe in the future.