The British business-investment series is titled Dragons' Den.
The title refers to the investor panel, whose members are called Dragons. Entrepreneurs enter the studio and present proposals in the hope of securing money, expertise and business connections. The possessive apostrophe is part of the official British title, although some informal references omit or reposition the punctuation.
The programme belongs to an international franchise descended from the Japanese format Money Tigers. Other countries have used different titles and local versions of the investor concept, including Shark Tank in the United States. Those programmes share broad format elements but are not the British series itself.
The title is also commonly written as Dragon's Den by people referring to the topic generally. The official British programme title uses the plural Dragons followed by an apostrophe: Dragons' Den. That distinction separates the name from a den belonging to one dragon.