What are some organizations dealing with the U.S. military?

I'm looking to get involved with an organization that deals with helping our military.... any branch, veterans, enlisted, family/friends, etc. So if anyone knows of any non profit organizations, charities, advocacy groups, or anything of that nature I'd really appreciate the help! I've been researching and know of a lot of the larger ones but I'd also like to know if there are any in NC (specifically Southeastern NC). Thank you!