Buzz Aldrin was the second man to walk on the moon, but his legacy far exceeds that triumph. A deeply complex man, Aldrin has not only conquered outer space but his own inner space: after his historic flight, he managed to pull himself out of a downward spiral of clinical depression and alcoholism, and is now a strong advocate for affordable health care access for other victims of mental illness. He's also one of the leading figures in the space colonization movement, using his fame as an astronaut to try to reignite the hope of a sustainable off-Earth community. As if that isn't awesome enough, Aldrin loves to spoof himself and has appeared in many films, video games, and TV shows such as The Simpsons, Futurama, and 30 Rock. But our favorite act of Aldrin badassery came in 2002, when the then 72-year-old Aldrin reacted to a moon-landing denier's over-the-top harassment by clocking him right out. Don't mess with Buzz, folks.