Not just for countries, Mary is the patron of an awful lot of things, by default, as it were. As I mentioned in another post a while back, Mom ends up picking up the slack a lot. Whenever you hear of “Our Lady of…” or “The Virgin of…”, that’s Mary.
Saint Uncle Sam
That’s not very funny, sorry.
Bibliophage: Admonition accepted. Mea culpa, mea culpa, mea maxima culpa.
That’s the popular legend. It’s not why he’s on the Roman and Orthodox calendars. He is on the official calendars because he was a great regularizer of Church practices in Ireland, securing its existence and administration from that point onwards.
What is this rubbish? Why do you go out of your way to insult the Orthodox Church?
Among the Orthodox, the most likely candidate would be St. Nicholas of Japan, the first Bishop of an Orthodox see in Japan. He came from Russia to Japan in 1861, while Christianity was still illegal. Christianity was legalized in Japan in 1872 and he was consecrated Bishop of Tokyo (I think) in 1878. During the Russo-Japanese war, his loyalty remained with his Japanese flock.
There are several saints who came from and lived in Arabia, but this was before Islam appeared. Thus the modern state of Saudi Arabia would have no explicit patrons among the Orthodox.
Serbia’s patron saint has always been Saint Sava–of course, he is Orthodox. I do not recall if Montenegro has one.
I’m sure not all the countries in the world have their own patron saints, it’s not as if the Vatican assigns them one when they declare their independence. This site says Yugoslavia had St. Cyril and St. Methodius as patron saints, but that was probably a pretty generic choice because they were apostles of all the Slavs anyhow.