James Watt, Scottish inventor, mechanical engineer and chemist (steam engine), born in Greenock, Scotland. He developed the concept of horsepower, and the SI unit of power, the watt, was named after him.
Watt attempted to commercialise his invention, but experienced great financial difficulties until he entered a partnership with Matthew Boulton in 1775. The new firm of Boulton and Watt was eventually highly successful and Watt became a wealthy man. In his retirement, Watt continued to develop new inventions though none was as significant as his steam engine work. He died in 1819 aged 83.