The UK series Dragon's Den was adapted from the Japanese business television format Money Tigers.
Money Tigers is known in Japan as Money no Tora. Its central format places entrepreneurs before wealthy businesspeople, who question the proposal and decide whether to invest. The British adaptation retained that central structure while changing the panel, business setting and presentation for its own audience.
Shark Tank is a different title used by some international adaptations of the same broad investment-show concept, especially in the United States. It is not the Japanese source title for the UK programme. Likewise, The Apprentice centres on employment tasks and business challenges rather than entrepreneurs pitching their own companies for investment. The precise source-format answer for the British Dragon's Den is Money Tigers.