You may have noticed that in Spanish, when you don’t know someone’s name, you can call them “Fulano” or “Fulana.” I mean, not to their face, but to refer to them. Like saying “Joe Blow” or “Jane Doe” or “John Q. Public,” it’s just a stop-gap word taking the place of a proper noun. “So-and-so,” essentially.
Like many Spanish words, “Fulano” comes from Arabic, in which language فُلَان “fulān” (feminine فُلَانَة or “fulāna”) is employed in the same way, for a person whose name one doesn’t know.
Fulān appears to be a cognate with the Hebrew term פְּלוֹנִי “p’loni,” meaning such and such, so and so, X person or thing. It appears several times in the Bible as one half of the expression “p’loni almoni” (פלוני אלמוני), used as a placeholder for an unknown name. Classical Syriac (a variety of Aramaic) has the very similar “plān” (ܦܠܢ), and Aramaic itself had the cognate דפלן (pln). Ultimately, these appear to derive from a Proto-Semitic root *pulān- that meant “person” some 6,000 years ago in Northern Africa.
And why the pseudo surname “de Tal”? That’s a little more straightforward, as it means “from such-and-such [a place]” (as in “un hombre de tal pueblo” or a man from such a town). There was a time when most last names derived from occupations or geographical locations, so it’s no surprise we’d use the construction with “fulano.”
Spanish has other words with a similar function, by the way. One is “zutano,” which comes from the Old Spanish “citano,” which evolved in turn from the Latin term “scitanus”, which ironically means … “a person or thing that is known.”
We also have Pérez y Mengano. “Pérez” is used like “John Smith” because it’s such a common surname. “Mengano,” on the other hand, comes from Arabic (like fulano). The original phrase was من كان “man kān” (literally, “Who was it?”).
And there’s even a fusion of these last two: “Perengano.”
When you string three of them together, you get the Spanish equivalent of “Every Tom, Dick and Harry”—Fulano, Mengano y Zutano.