Which Dragon was known for the slogan “I’m out” when declining a Dragon’s Den pitch?

Duncan Bannatyne was known for saying “I’m out” when declining a Dragon’s Den pitch.

The phrase became one of the programme’s recognisable verbal signals. When a Dragon said it, the investor was withdrawing from consideration and would not make an offer for the entrepreneur’s business. Bannatyne’s direct style made the expression particularly associated with him in popular memory.

Bannatyne is a Scottish entrepreneur whose business interests included health clubs, hotels and care homes. He joined the British Dragon’s Den panel in the programme’s early years and became one of its most recognisable investors.

Other Dragons also used the phrase because it describes a standard part of the format, so it is not an exclusive catchphrase. The question identifies the Dragon most strongly associated with its repeated use, rather than claiming that nobody else ever said it.