Steve Jobs is a tough act to follow, but in the six years since Jobs' death, Tim Cook has proved he’s more than up to the task of running the richest corporation in the world.

Under Cook’s guidance, Apple became the first U.S. company to hit $800 billion in market value, and it’s only going up, as the company continues to roll out innovative products consistent with Jobs’ vision. But Cook is his own man.

The first openly gay CEO of a Fortune 500 company, the 56-year-old tech executive is committed to environmental causes and has vowed to eventually donate his entire stock fortune, estimated to be more than $500 million, to charity.