New to the Forbes list this year was Kylie Jenner, whose growing wealth from her Kylie Cosmetics are on track to make the 21-year-old the youngest a billionaire. Jenner was tied with rapper Jay-Z at No. 5, each with fortunes estimated at $900 million. Kylie Kristen Jenner (born August 10, 1997) is an American reality television personality, model, entrepreneur, socialite, and social media personality. She has starred in the E! reality television series Keeping Up with the Kardashians since 2007 and is the founder and owner of cosmetic company Kylie Cosmetics.