He's the guy who chained himself to the front gates of Saddam Hussein's palace in downtown Baghdad two days before the 1st Gulf War began. He claimed he wasn't going to move, but would stay there as a human shield to protect the Iraqi government palace.

The U.S. military got a message to Sean Penn... advising him not to be there when the clock ran out. He decided he protested long enough, and left 1 day before the bombing began. :>)

Sean Penn is also the guy who brought a rescue boat into New Orleans after Hurricane Katrina. He was involved in the rescue of two families... and made sure it was filmed from multiple angles. They got film of Sean helping people off the boat (which I'm sure they had to shoot it several times to get his good side)... then they interviewed the families and how grateful they were to Sean.
After those two families were rescued... Sean Penn got the "hero" film he wanted, so he left New Orleans that same day and went back to Hollywood.

If you think that Sean Penn cares about anyone but himself... you are delusional.