Why is Rider called "Iskander" instead of "Alexander"? The true identity of Rider in Fate/Zero is Alexander the Great, the famed conqueror and King of Macedonia. Since Alexander conquered so many countries, his name has been adapted to many different languages, including Arabic, Persian, and Turkish, in which he's known as Iskandar, Eskandar, and İskender. (Source.)

The page I linked says the Japanese forms of the name are "アレクサンドロス (Arekusandorosu), アレクサンダー (Arekusandā), アレキサンダー (Arekisandā)" which are all based on the Greek form, Ἀλέξανδρος (Alexandros), or the English/general European form, Alexander. Did the staff ever publish any statements about why Rider is called by a Middle Eastern form of his name, Iskander, instead of using one of the European forms based on "Alexander"?

(Note: If the answer contains spoilers for Season 2, please use spoiler tags, or at least warn me at the top.)
While I don't know if Gen Urobuchi had said anything about this, the TYPE-MOON Wikia page for Rider (under Profile section, since you know his real name the first paragraph shouldn't be too bad in terms of spoilers) says his name was also Al-Iskandar which does kinda sound like Alexander.

But then that doesn't answer why they choose that name. This is just speculation on my part, however Iskandar is derived from the Old Persian name Sikandar. Old Persian have been used in Achaemenid Empire at the time of Alexander's conquests, and it should be noted that the Achaemenid Empire was one of the largest empires in the world in terms of how many people it ruled.


  Darlus ruled about 50 million people in the largest empire the world had seen (Meyer, p.85)


And Wikipedia lists it as the second largest in terms of % of the world population


  44.48% (50 million out of 112.4 million in 480 BC)


I would assume Alexander's name being Al-Iskandar (or just Iskandar) is a note to one of his greatest achievements: his victory against the Achaemenid Empire.