Catherine the Great
ruled Russia for 34 years. She was not native to Russia, but went on to become a powerful and emblematic leader. A recent biography by Robert K. Massie adds to that author's distinguished list of works about the Russian royalty.
From the article:
She began life in 1729 as a very minor German princess named Sophia, but her ambitious mother managed to arrange a marriage to the heir to the Russian throne. At 15, Sophia was taken to St. Petersburg, began studying Russian, converted to Orthodox Christianity without much fuss and was renamed Catherine.
I haven't read the book, but I believe it was the Emperor Frederick of Prussia that arranged the marriage, and it had nothing to do with her mother. Actually her meddling in affairs was a cause of consternation to the Emperor as well as to the Russian Empress Elizabeth. I love to delve into history and I believe, although I have no source to back it, that the Emperor chose her because of her Byzantine ancestry since it would make her more desireable to the Russian people. I say this because the Greek kings had always been able to trace their ancestry to Roman nobility through Queen Olga, who inherited it from Catherine the Great.
Anyway Catherine's 'smarts' were certainly Byzantine, and Russia did turn into a formidable power because of her.