Which Dragon's Den investor was known by the nickname Theo?

The Dragon's Den investor known by the nickname Theo was Theo Paphitis.

Theo Paphitis is a Greek-Cypriot British retail entrepreneur who became one of the programme's best-known investors. His business career included major involvement in retail brands, and his Dragon's Den appearances made his direct questioning and interest in consumer businesses familiar to a broad television audience.

The name Theo is sometimes mistaken for a separate surname or confused with another Dragon because the panel included several investors with prominent first names and business backgrounds. The complete name is Theo Paphitis. He joined the programme after its launch and became part of the established investor line-up.

Paphitis's television role reflected the programme's central idea: an entrepreneur must persuade an investor that a business has both commercial potential and an acceptable valuation. A Dragon could make an offer, negotiate terms, or decline to invest, so appearing on the show did not guarantee funding.