Dragutin Dimitrijevic (known as Apis) – he killed one king, one heir and is somewhat responsible for beginning of WWI; ca. 1914.
Dragutin Dimitrijević (Serbian Cyrillic: Драгутин Димитријевић; 17 August 1876 – 24 June 1917), also known as Apis (Апис), was a Serbian colonel. He was a leading member of a military group that organized the overthrow of the Serbian government in 1903. He personally organized and participated in the coup against King Alexander and his wife Queen Draga that resulted in their murders, though he was not present when they were killed. He was also the leader of the Black Hand group responsible for the assassination of Franz Ferdinand, Archduke of Austria in June 1914. The latter triggered the July Crisis which led to the outbreak of World War I.