Stanley Clark Bagg was born on December 23, 1820, in Montreal, Quebec.

He was a wealthy Canadian notary and one of the largest landowners on the island of Montreal. He graduated from McGill University. In 1842, he became a notary and practiced in Montreal until 1856. After that date, he managed the real estate he inherited from his father. He donated many of these lands to the city to develop streets and public squares, e.g. Jarry Park. A loyalist, Bagg participated in the Battle of Saint-Eustache during the 1837-1838 rebellions in Lower Canada. He was later considered a close associate of the Conservative Party led by John Alexander Mackenzie. In 1859, he became a justice of the peace. He was also one of the founders of the Montreal Archaeological and Numismatic Society in 1866 and served as its first president. He published several works on the subject, including “Notes on Coins [...]” (1863), “Coins and Medals as Aids to the Study and Verification of Holy Writ” (1863) and “The Antiquities and Legends of Durham” (1866).
The Stanley Bagg Corporation is the real estate company founded in Montreal in 1919 by the heirs of Stanley Clark Bagg.

In 1844, he married Catherine Mitcheson. He died on August 8, 1873, in Montreal, Quebec.