Global DEBT - who benefits from it? Who is is the ultimate LENDER?

I was wondering - if all nations are in DEBT then who is the MONEY LENDER?

Looking on the following websites:
http://www.economist.com/content/global_debt_clock
http://www.nationaldebtclocks.org/

I can see that all countries are in RED, they have debt and I cannot find the source of it. In my opinion there should be one nation (or an institution - like e.g. IFM) who is the DEBT issuer.