American human rights activist currently serving as a program associate at the National Democratic Institute and an ombudsman of the World Liberty Congress, a global coalition of pro-democracy leaders.

She studied at the City University of Hong Kong, where she emerged as a key figure in the 2019–2020 pro-democracy protests, serving as spokesperson for the Hong Kong Higher Institutions International Affairs Delegation (HKIAD). In this role, she lobbied internationally against the Hong Kong extradition bill, meeting with policymakers in the United States, the United Kingdom, Germany, and the European Parliament.

Beyond her grassroots activism, Siu has remained a prominent advocate for Hong Kong’s democracy movement on the global stage. She has spoken at international forums such as the Summit for Human Rights and Democracy in Geneva and the Oslo Freedom Forum. In 2023, Hong Kong authorities issued an international arrest warrant for her, making her the first U.S. citizen declared a fugitive under the Hong Kong National Security Law. Despite ongoing threats and transnational repression, she continues her advocacy, reaffirming her commitment to defending human rights and democracy.