7. Anton Kathrein, Jr.
Net worth: $1.7-billion
A pioneer in automotive antennas in the 20th century, Kathrein-Werke – Anton Kathrein, Jr. is the third generation to lead the company – has become a key player in mobile communications as service providers have expanded their networks to accommodate rapid growth in data traffic and users. With revenue of more than $1.6-billion in 2013, it makes the cables, antennas and receivers that allow cell phone signals to bounce across the world.
8. Elizabeth Holmes
Net worth: $4.5-billion
Elizabeth Holmes makes her debut on the list as the youngest self-made woman billionaire. She dropped out her sophomore year of Stanford University to found Palo Alto, California-based blood testing company Theranos in 2003 with money she saved for college. Theranos has raised $400-million from venture capitalists, valuing the company at $9-billion, and Holmes’ 50% stake at $4.5-billion.
9. Tatiana Casiraghi
Net worth: $2.2-billion
Tatiana Casiraghi is a billionaire heiress and member of Monaco’s royal family, married to Andrea Casiraghi, who is reportedly second in line to the throne. Although she married into royalty, Tatiana was rich long before her wedding. Her grandfather Julio Mario Santo Domingo had owned Colombian brewery Bavaria before trading it for 15% of SABMiller in 2005.
10. Nathan Blecharczyk
Net worth: $1.9-billion
Nathan Blecharczyk is co-founder and chief technology officer of Airbnb, which lists 1,000,000 homes (or rooms in people’s houses or apartments) for rental stays; 30 million guests have used the service since it launched in 2008. Airbnb raised $450-million in April 2014, valuing the company at $10-billion and Blecharczyk’s stake at $1.5-billion. It’s since inched up in an employee share sale that valued the company at $13-billion in October 2014.
11. Ryan Graves
Net worth: $1.4-billion
Ryan Graves was the first employee hired at Uber, the ride-hailing service now valued at $41.2-billion. Uber is competing with taxi services across the US and in 53 other countries around the world. Graves joined Uber in 2010 when Travis Kalanick (who is now worth $5.2-billion, but at 38 years old features much later in the full list) Uber’s co-founder and current CEO, tweeted that he was looking for a product manager.
12. Drew Houston
Net worth: $1.2-billion
Dropbox co-founder and CEO Drew Houston is one of Silicon Valley’s newest boy-wonder billionaires. Houston co-founded the cloud-based file-sharing service with Arash Ferdowsi in 2007. Investors include venture capital firms Sequoia Capital, Index Ventures and Accel Partners as well as Goldman Sachs and BlackRock.