Jamaican-British entrepreneur Keith Valentine Graham used the stage name Levi Roots when he appeared on Dragons' Den.
Roots became widely known after pitching his Reggae Reggae Sauce on the programme in 2007. The pitch combined his food business with his musical identity: he is also a reggae musician, and “Levi Roots” is the name under which he performs and promotes his brand.
The television appearance helped turn the sauce into a major commercial brand. Roots secured investment from Peter Jones and Richard Farleigh, and the product subsequently expanded beyond its original market into broader retail distribution and a wider range of Caribbean-inspired foods.
The answer is a stage name rather than the entrepreneur's birth name. That distinction is why the question identifies Keith Valentine Graham explicitly. “Levi Roots” is the public name attached to the musician, entrepreneur and food brand, while the other names are not his established professional identity.