Boonpeng (1890 – August 19, 1919), popularly known as Boonpeng Heep Lek (Thai: บุญเพ็งหีบเหล็ก, RTGS: Bunpheng Hip Lek) or Iron-Chest Boonpeng, was a Thai murderer and suspected serial killer who killed between two and seven religious worshippers in 1917. Convicted for these killings, he was beheaded in 1919, the last public execution conducted in the country.