AGE: 55
OCCUPATION: Microsoft co-founder, tech entrepreneur
NUMBER OF TIME COVERS: 0
PREVIOUS APPEARANCES ON THE TIME 100: 1
PRO: He's underwritten the Ansari X Prize, mapped the genetics of the mouse brain, engineered the spin-off of DreamWorks Animation, fought a successful lawsuit to return Jimi Hendrix's music rights to his family, and kept the Seahawks in Seattle. Heroic capitalism is his creed.
CON: Exited the Forbes Top 10 Richest Americans list this year. (He's number 11.) His Microsoft shares have taken a tumble, and many of his kookier ventures failed to pay off.