From Wikipedia, the free encyclopedia Semion Yudkovich Mogilevich[1] (Ukrainian: Семен Ю́дкович Могиле́вич, tr: Semen Yudkovych Mohylevych, [sɛmˈɛn ˈjudkɔwɪt͡ʃ mɔɦɪˈlɛwɪt͡ʃ]; born June 30, 1946) is a Ukrainian-born organized crime boss, believed by European and United States federal law enforcement agencies to be the "boss of bosses" of most Russian Mafia syndicates in the world.[2] Mogilevich is believed to direct a vast criminal empire and is described by the FBI as "the most dangerous mobster in the world".[3][4] He has been accused by the FBI of "weapons trafficking, contract murders, extortion, drug trafficking, and prostitution on an international scale."[5]