Jan Letzel (9 April 1880 – 26 December 1925) was a Czech architect who was active in early 20th century Japan.

He is most famous for designing the Hiroshima Products Exhibition Hall that was partially destroyed in the atomic bombing of the city.

The ruins of the Exhibition Hall is now the Hiroshima Peace Memorial, also known as the A-Bomb Dome, a UNESCO World Heritage Site.

After a short stay in Prague and Náchod, he arrived in Tokyo in June 1907, where he worked at a French architectural firm.

When his partner Karel Hora returned to Bohemia in 1913, Letzel led the architecture firm alone, but in 1915 he had to give up the work due to World War I.