5. Hero of Alexandria
This man could have started the Industrial Revolution in 50 AD with the invention of the Aeolipile, a form of steam or jet engine where jets of steam spin a ball. However, he failed to realize what the device could do, and thought of it as nothing but a toy. Some have speculated that the abundance of slave labor negated any need for a labor-saving device, so no one applied his device in the manner of the Industrial Revolution. Hero also wrote many works on subjects ranging from pneumatics to mathematics to physics.