William Mason (September 2, 1808 – May 21, 1883) was a master mechanical engineer and builder of textile machinery and railroad steam locomotives.

His company was a significant supplier of locomotives and rifles for the Union Army during the American Civil War.

He left home at the age of thirteen and worked as an operator in the spinning room of a small cotton factory in Canterbury, Connecticut.

At the age of sixteen he went to East Haddam, where a mill for the manufacture of thread was being established, to start the machines.

In 1833, Mason joined Asell Lamphaer at Killingly, Connecticut, to make the ring-frame for spinning.

[2] In 1835, Mason moved to Taunton, Massachusetts, to join Crocker and Richmond, manufacturers of cotton machinery.

Competition required improvements and on October 3, 1846, he received a patent for "Mason's Self-acting Mule.

Leach and Keith suffered a failure in the winter of 1842 owing Mason a large amount of money.

James K. Mills & Co. of Boston, a leading commission firm, came to his rescue and helped him to buy out the former partners.