Peter Jones was the only original Dragon's Den investor to appear in every series up to 2024.
Jones was part of the original five-member panel when the British programme began in 2005. The other launch investors were Duncan Bannatyne, Rachel Elnaugh, Theo Paphitis and Doug Richard, all of whom eventually left the regular panel.
His continuous presence is one reason Jones is strongly identified with the UK format. Across the programme's changing line-ups, he has remained a link between the first series and later eras that introduced investors such as Deborah Meaden, Sara Davies and Steven Bartlett.
This question uses “original investor” to mean a member of the launch panel, not the first dragon to make a particular deal or the longest-serving investor in every international version. Dragon's Den has separate adaptations around the world, with different panels and broadcast histories. The answer therefore concerns the British BBC series and its regular panel through 2024.