The wealthy investors on the British television programme Dragon's Den are called dragons.
The term is part of the programme's identity and refers to the businesspeople who listen to pitches, ask questions and decide whether to invest. Entrepreneurs typically request a sum of money in exchange for a percentage of their company, allowing the dragons to negotiate the proposed deal.
The terminology changes between international versions of the format. The US adaptation uses sharks, while the original Japanese programme used a different animal reference. Those names are related through the shared format but are not the canonical term for the British panel.
The plural answer is appropriate because the programme features a panel rather than a single investor. Individual panel members are identified by name, but the collective label used in the British title and description is dragons.