http://www.livescience.com/44186-who-invented-the-steam-engine.html
In a world propelled by combustion engines, gas turbines and nuclear reactors, the steam engine may seem like a relic of the past. But without this game-changing invention, the modern world would be a much different place.
Arguably the most important development of the Industrial Revolution, the steam engine facilitated major advancements in the fields of mining, manufacturing, agriculture and transportation. And while several prominent figures of the 18th and 19th centuries are credited with developing and improving the steam engine, the history of steam-powered machines actually goes back nearly 2,000 years before the Industrial Revolution.
Ancient steam turbines
Early in the first century A.D., a Greek inventor named Hero of Alexandria designed the world's first aeolipile, or primitive steam turbine. Heron's aeolipile consisted of a hollow sphere, mounted on a pair of tubes. Heated from below by fire, the tubes transported steam to the sphere, where it was released through another series of tubes projecting from the sphere's equator. This movement of steam through the device caused the sphere to revolve, demonstrating the potential for using steam as a means of propulsion.