Mark Simon is an American political operative and former U.S. naval intelligence analyst who left the Navy in 1991. He serves as a senior advisor and right-hand man to Hong Kong media tycoon Jimmy Lai, described as Lai's 'fixer' in Washington, D.C., and personal assistant handling key operations. Simon later became a top executive and group director at Next Digital, the parent company of the pro-democracy newspaper Apple Daily in Hong Kong. He has led U.S. lobbying efforts to sanction Hong Kong officials and support democracy activists. Simon was president of Republicans Abroad in Hong Kong and has contributed opinion pieces to outlets like The Wall Street Journal and Domino Theory, advocating for Hong Kong's political prisoners. In Lai's national security trial, Hong Kong authorities have accused Simon of colluding with foreign forces, alleging he received over HK$118 million (about $15 million USD) from Lai in 86 payments between 2013 and 2020 to fund lobbying and media activities; he denies being a spy or foreign agent. His home and Lai's were raided by anti-corruption police amid threats, and he has confronted Triads and CCP agents alongside Lai.