Castle Rock, known until 2007 as Tynemill is a British pub chain based in Nottingham and the East Midlands. It was founded in 1977 by former Campaign for Real Ale (CAMRA) chairman Chris Holmes. Their first pub was the Old King Arms in Newark. They have won the "Pub Group of the Year" award in 2002, 2006, and 2008.
They operate several pubs or cafe bar establishments which all have a policy of selling cask beers from regional and local microbreweries. They also own and operate the Castle Rock Brewery, a microbrewery located in Nottingham. The old Tynemill brand name for the pubs has now been replaced by Castle Rock.