The steam engine was invented by Thomas Newcomen, an English engineer, in 1712. His invention is known as the "Newcomen engine" or the "atmospheric steam engine." While Thomas Newcomen is credited with the invention of the first practical steam engine, it's important to note that significant improvements and innovations in steam engine technology were made by James Watt in the later 18th century, which greatly increased its efficiency and practicality for various industrial applications.