Peter Jones has served continuously on the British Dragon's Den panel since the programme's first series.
Jones was one of the original investors when the BBC show launched in 2005, and he remained a panel member as other dragons joined and departed. His long tenure made him the constant link between the early series and later versions of the programme.
He is a British entrepreneur and investor whose business interests have included technology, media, leisure, and retail. On Dragon's Den, he is often associated with evaluating scalable products and consumer businesses, although his televised offers have covered many different sectors.
“Continuously” is important: several prominent dragons have appeared for multiple series, but not all were present from the launch onward. The answer refers to the regular British panel, not guest investors or dragons from overseas editions.