Joost Bürgi (February 28 1552 - January 31 1632) was a Swiss clockmaker and mathematician. He is sometimes regarded as the inventor of the logarithm, although credit often goes to John Napier instead.

Bürgi was born in Lichtensteig , Switzerland and died in Kassel, Hesse-Kassel (now part of Germany).

The lunar crater Byrgius is named in his honor.