Mostly the Xe (formerly Blackwater) security guards contracted to protect him...?
Related and worth a read:
In the same vein:
How Did bin Laden Live Undetected in Pakistan for Years? Someone Has Got Some Explainin' to Do.
With regard to the spectacular killing
Of Osama bin Laden last Sunday
Authorities there should all insist they
Had plans to kill him last Monday.
Yeah, the next time he ordered in, they were gonna send a squad of commandos disguised as the pizza delivery guy. Yeesh.