William Trench III (October 21, 1831 - April 12, 1896) was the reeve of Richmond Hill, Ontario from 1875–1879 and 1881 - 1882.

[1] Born in Dunbar, Scotland, Trench came to Elgin Mills, Ontario with his family in 1842.

Trench learned the blacksmith trade from his father and set up a shop in Richmond Hill in 1857.

[4] Trench manufactured buggies, wagons, stagecoaches, and carriages used in the mid to late 19th Century Ontario, but would go out of business in the 1920s due to the movement towards automobiles[5] Trench Street in Richmond Hill is named in his honour.

[7] The buildings that housed the business remains in use as retail shops at 10117, 10119 and 10123 Yonge Street (southeast corner at Yonge Street and Lorne Avenue).