Samuel Smith Old Brewery, commonly known as Samuel Smith's or Sam Smith's, is an independent brewery and pub operator based in Tadcaster, North Yorkshire, England, established in 1758. It claims to be Yorkshire's oldest brewery.

It is known for being traditionally run with conservative values, still using dray horses for some beer deliveries, and banning music, television and mobile devices in its bars.

Tadcaster had been a centre for brewing since the 14th century because of its gypsum rich wells. The Old Brewery was established as the Backhouse & Hartley Brewery in 1758.

In 1847, John Smith, supported by his father, a butcher and cattle dealer from Meanwood, purchased it and built his new John Smith's Brewery close by. John Smith's brother William, who ran the business after John's death in 1879, left the Old Brewery to his nephew Samuel in 1886. However, Samuel inherited an empty building and well, with all equipment having been moved next door. Nevertheless, he refitted and opened his brewery.

Samuel Smith traditional bottled beer styles influenced American craft brewers such as Goose Island and Brooklyn Brewery in the late 1970s and early 1980s.

In 1982, the company took the "extraordinary" step of changing itself from a standard limited liability company to an unlimited company, making its owners personally liable for all debts. As a result, the company is no longer required to publish its financial accounts, and has not done so since.

Since 2000, the "publicity-shy" company has dropped the Samuel Smith name across their pubs, with staff also told not to wear Samuel Smith branded t-shirts behind the bar.

The Old Brewery is the smallest of three current Tadcaster breweries and one of the few remaining British breweries to employ a traditional, 19th century, Yorkshire Square fermentation system constructed of Welsh slate.