Jeff Bezos was a solo founder when he started Amazon in 1994. Employee #1 (Shel Kaphan) was brought on before incorporation, but says Jeff was the founder (http://www.geekwire.com/2011/meet-shel-kaphan-amazoncom-empl...)
Andrew Mason was a solo founder of Groupon, started with $1 million seed money from a former employer.
Jeff Bezos was a solo founder when he started Amazon in 1994. Employee #1 (Shel Kaphan) was brought on before incorporation, but says Jeff was the founder (http://www.geekwire.com/2011/meet-shel-kaphan-amazoncom-empl...)