Keyser Soze is the supposed criminal mastermind behind the events in the movie The Usual Suspects. He is supposedly Turkish or German. His interests in the criminal world are mainly drugs and dealing illegal goods to countries, such as parts for nuclear plants.
Keyser Soze should probably be spelled Keyser Söze considering that he is supposedly Turkish. Now following from the logic that Keyser Söze is Turkish-German, since he did live in Turkey (Turkiye).
I'm warning you...
Alright, but don't say that I spoiled The Usual Suspects for you.
Keyser. The pronunciation is very similar to that of the German word Kaiser. Kaiser means "King" or "Emperor" in English (coming from the Latin word Caesar).
Söze. This is a Turkish word, basically meaning speech.
Put the two together and since possession is very subjective in Turkish (not sure about German), you can come up with "King of Speech."
Hmm... "Verbal." Roger "Verbal" Kint. There was a clue since the beginning.