Jan Koum
Entrepreneur
Ukraine-American developer who co-founded WhatsApp in 2009. In 2014 he entered the Forbes list of the 400 richest Americans, with an estimated worth of over $7.2 billion.
He studied at San Jose State University, but left before graduation after being hired by Yahoo! as an infrastructure engineer.
In 2014 Facebook acquired WhatsApp for $19 billion.
He moved to America in 1992 with his mother and grandmother. His father planned to join them, but passed away in the Ukraine in 1997.
In 1996 he was a member of hacking group w00w00 with Napster founder Shawn Fanning.