morFing
I found a site that translates exactly "El Greco" into "The Greek". But the link I can I copy shows the main page only.. So go to the first site (freetranslation), choose Spanish (European) to English, type the phrase, choose "Free translation" and you'll have the results you need! I understand it is hard to find an exact translation, as 'griego' is more used than 'greco' in Spanish, and more sites don't even translate the word 'greco'! Maybe it is obsolete. But spanishdict does. Check it as well. I hope I helped.

CML
Domenico Theotokopoulos was born in the island of Crete when this was under Venetian rule. He continued his studies first in Italy, where he applied to the St. Lucas Painters Guild under the name Domenico Greco. His was known as El Greco after his death. Greco means Greek in Italian, and 'El' is how Spanish people called him, or maybe from a venetian dialect. So Greco is not Spanish, but Italian -- but this word works now as a name for Theotokopoulos. Only the article is (most probably) spanish. wikipedia [in greek] \ γραικός or graecus means greek