Who Is Henry Gale?

When mysterious island inhabitant 'Henry Gale' first appeared in LOST, he was ensnared in a booby trap set by Danielle Rousseau. I pitied the man when he was shot and wounded by the said 'crazy Frenchwoman'. But when he was later revealed to be one of 'The Others' (and a significant one, too), I was flabbergasted. In essence, 'Henry Gale' exists amongst all of us. They would be those people we trustfully allow into our lives, unaware of their hidden agendas - that is, until the truth smacks us in the face. So, do you know any 'Henry Gale'?