Prince Nicholas of Greece and Denmark was the son of which king that was assassinated in 1913?  
Prince Nicholas of Greece and Denmark: Prince Nicholas of Greece and Denmark (, 22 January 1872 – 8 February 1938), of the Glücksburg branch of the House of Oldenburg, was the fourth child and third son of King George I of Greece, and of Queen Olga. George I of Greece: George I (Greek: Γεώργιος Α΄ , "Geórgios I"; born Prince William of Schleswig-Holstein-Sonderburg-Glücksburg; 24 December 1845 – 18 March 1913) was King of Greece from 1863 until his assassination in 1913.
George I