Dirk Hartog (baptized 30 October 1580, Amsterdam – buried 11 October 1621, Amsterdam) is a 17th century Dutch sailor and explorer.

Dirk Hartog's expedition is the third European group to land on Australian soil.

He is the first to leave behind an artifact to record his visit, the Hartog plate.

His name is sometimes alternatively spelled Dirck Hartog or Dierick Hartochsz.

Ernest Giles referred to him as Theodoric Hertoge in Australia Twice Traversed (1872).

Born into a seafaring family, at the age of 30 he receives his first ship's command, and spends several years engaged in successful trading ventures in the Baltic and Mediterranean seas.