Peter Jones is the only original Dragon to have remained on the British Dragon's Den panel throughout the series.
Jones was part of the original investor lineup when the BBC programme began in 2005. Other early Dragons left the regular panel or were replaced as the series developed, while Jones continued to appear as a central investor.
His television role is connected to a broader business career involving technology, media and consumer ventures. On the programme, he is often recognised for examining how a product could scale, how much ownership an entrepreneur is offering and whether the proposed valuation is realistic.
The word “original” matters here: the show has had many later Dragons, and several became strongly associated with particular series. That does not make them members of the initial panel, which is why Peter Jones is the specific answer.