In the British show Dragon's Den, the investors' nickname for the pitch room is “The Den.”
The title supplies the programme's central metaphor: entrepreneurs enter a den occupied by investors known as dragons. They stand before the panel, explain their business and ask for a specified investment in exchange for an ownership share.
The room is a television studio set rather than an actual cave or permanent business office. Its dark, dramatic design supports the programme's branding and distinguishes the British format from adaptations that use different imagery and names.
A frequent mix-up is “the Tank,” which belongs to the American adaptation Shark Tank. The British show uses “the Den,” while the investors are “Dragons.” These terms describe the programme's own branding and should not be transferred between versions.