Thomas Stelzer (born June 19, 1955) is an Austrian diplomat, who served as the Dean and Executive Secretary of the International Anti-Corruption Academy (IACA) until March 2024.

Stelzer holds a doctorate in law from Vienna University, a master of arts in Latin American studies from Stanford University, and a diploma in international relations from the Johns Hopkins University, School of Advanced International Studies, Bologna Center.

Stelzer served in a variety of diplomatic and international positions.

Minister-Counsellor at the Permanent Mission of Austria to the United Nations in New York; Delegate to the Committee for Disarmament and International Security (First Committee) of the General Assembly;Austrian Representative to the governing bodies of the United Nations Development Programme (UNDP), the United Nations Children’s Fund (UNICEF) and the United Nations Population Fund (UNFPA);

Deputy Director of the Austrian Cultural Institute in New York;

Special Assistant to the Executive Secretary of the CTBTO (Comprehensive Nuclear Test-Ban Treaty) Preparatory Commission;

Permanent Representative of Austria to the United Nations (Vienna), United Nations Industrial Development Organization (UNIDO), International Atomic Energy Agency (IAEA), and the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) Preparatory Commission;

Facilitator and Chair of the Vienna Terrorism Symposiums;