Theodorus of Samos was a Greek sculptor and architect of the sixth century BC who is often credited with the invention of ore smelting and, according to Pausanius, the craft of casting. He is also credited with inventing a water level, a carpenter's square, and, according to Pliny, a lock and key and the turning lathe.

In some texts he is described,above all, as a great artist and in some statues he is depicted as a great inventor.