Peter Jones has been the only original Dragon still appearing on the regular Dragon's Den panel since the British series began.
Jones joined the original panel when the BBC series launched in 2005. He became one of its best-known investors, often discussing technology, retail, consumer products and business scaling during pitches.
The original panel also included Duncan Bannatyne, Rachel Elnaugh, Simon Woodroffe and Doug Richard. Those investors subsequently left the programme, while later Dragons joined for different periods. Jones therefore became the enduring link between the first series and later versions of the show.
This fact concerns the regular British programme, not every guest or substitute investor who has appeared. It is also different from asking which Dragon has made the largest investment or which investor has the highest personal wealth; those comparisons depend on definitions and changing information.