In general, the words "credible and reputable" do not describe loan sharks. If you want to find a true loan shark, you probably should ask narcotics users or gamblers to speak to their dealers or bookies. Usually loan sharking is run by mafias or other organized criminal gangs, so if you can find a person connected to organized crime, he/she should be able to help you find a contact. Be careful though; that drug dealer or bookie who links you to a loan shark will probably want a cut. Banks would call this cut an "origination fee."
You may want to try a bank instead. The 2008 financial crisis still casts a dark shadow over the banking industry and its once mediocre reputation as the engine of a speculation-driven period of growth in the mid-2000s. Some critics might even pejoratively call banks legalized loan sharks. If you default on your loan, the bank will likely pester you, then sell your loan to a collections agency, which might sue you. If you default on a loan shark's loan, your credit score will not be affected, but you may find that your life--or a relative's life--is in danger. All that said, a personal loan from a bank would be dischargeable in bankruptcy, while your debt to a loan shark would likely only be forgiven in the event that your loan shark is imprisoned or killed by a rival criminal group. Of course it is possible that you could face prosecution for your complicity in a criminal enterprise.
If you have bad credit and need a loan, you could try the social investing site www.prosper.com.
There are pros and cons to each of these options. I would recommend consulting both a certified financial planner and a tax adviser before making a decision.