The room where entrepreneurs pitch to investors on the UK show Dragon's Den is called the Den.
The Den is the programme's central setting: entrepreneurs enter, introduce themselves and present their businesses to the investor panel. The name is also a direct part of the show's title, using the image of Dragons guarding a territory and deciding whether a proposal deserves support.
Pitches normally include a requested investment and an offered percentage of the business. The Dragons then question the founders about sales, margins, valuation and growth before deciding whether to make an offer.
The setting is sometimes casually called a boardroom because business negotiations take place there, but boardroom is not the programme's canonical name. The show's own terminology is simply “the Den,” which is why the title uses the possessive form Dragon's Den.