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Obama isn’t a king, he’s a czar.

czar (n.) 1550s, from Russian tsar, from Old Slavic tsesari, from Gothic kaisar, from Greek kaisar, from Latin Caesar. First adopted by Russian emperor Ivan IV, 1547.

The spelling with cz- is against the usage of all Slavonic languages; the word was so spelt by Herberstein, Rerum Moscovit. Commentarii, 1549, the chief early source of knowledge as to Russia in Western Europe, whence it passed into the Western Languages generally; in some of these it is now old-fashioned; the usual Ger. form is now zar; French adopted tsar during the 19th c. This also became frequent in English towards the end of that century, having been adopted by the Times newspaper as the most suitable English spelling. [OED]

The Germanic form of the word also is the source of Finnish keisari, Estonian keisar. The transferred sense of "person with dictatorial powers" is first recorded 1866, American English, initially in reference to President Andrew Johnson. The fem. czarina is 1717, from Italian czarina, from Ger. Zarin, fem. of Zar "czar." The Russian fem. form is tsaritsa. His son is tsarevitch, his daughter is tsarevna.

tsar (n.) 1660s, the more correct Latinization of Russian czar, from prehistoric Slavic *tsesar, from a Germanic source, ultimately from Latin Caesar. See czar.

And

Caesar 1200, see caesarian; Old English had casere, which would have yielded modern *coser, but it was replaced in Middle English by keiser, from Norse or Low German, and later in Middle English by the French or Latin form of the name. Cæsar was used as a title of emperors down to Hadrian (138 C.E.), and also is the root of German Kaiser and Russian tsar (see czar). He competes as progenitor of words for "king" with Charlemagne (Latin Carolus), as in Lithuanian karalius, Polish krol. In U.S. slang c.1900, a sheriff was Great Seizer.

http://www.etymonline.com/index.php?allowed_in_frame=0&search=czar&searchmode=none