BK is the common abbreviation for the Burger King chain of fast food restaurants.

Burger King, often abbreviated as BK, is an American global chain of hamburger fast food restaurants headquartered in unincorporated Miami-Dade County, Florida, United States. The company began in 1953 as Insta-Burger King, a Jacksonville, Florida-based restaurant chain. After Insta-Burger King ran into financial difficulties in 1954, its two Miami-based franchisees, David Edgerton and James McLamore, purchased the company and renamed it Burger King. Over the next half century, the company would change hands four times, with its third set of owners, a partnership of TPG Capital, Bain Capital, and Goldman Sachs Capital Partners, taking it public in 2002. In late 2010, 3G Capital of Brazil acquired a majority stake in BK in a deal valued at US$3.26 billion. The new owners promptly initiated a restructuring of the company to reverse its fortunes. 3G, along with partner Berkshire Hathaway, eventually merged the company with Canadian-based doughnut chain Tim Hortons under the auspices of a new Canadian-based parent company, Restaurant Brands International.

The Federal Criminal Police Office , abbreviated .BK, is the federal police force in the Republic of Austria. Its role is to combat crime nationwide and serve as a center for cooperation with international police functions. Created in 2002 under a special law called the Federal Investigation Bureau Law , the .BK is also sometimes referred to as the Austrian Criminal Intelligence Service. It should not be confused with the Federal Criminal Police Office of Germany which is also called the Bundeskriminalamt but abbreviated BKA.