A bureau of the US Department of the Treasury.

http://www.occ.treas.gov/index.html

The OCC's primary mission is to charter, regulate, and supervise all national banks and federal savings associations. The OCC also supervises the federal branches and agencies of foreign banks. The goal in supervising banks and federal savings associations is to ensure that they operate in a safe and sound manner and in compliance with laws requiring fair treatment of their customers and fair access to credit and financial products.

In regulating national banks and federal thrifts, the OCC has the power to: examine the national banks and federal thrifts; approve or deny applications for new charters, branches, capital, or other changes in corporate or banking structure; take supervisory actions against national banks and federal thrifts that do not comply with laws and regulations or that otherwise engage in unsound practices; remove officers and directors, negotiate agreements to change banking practices, and issue cease and desist orders as well as civil money penalties. The OCC in 2011 assumed the responsibilities of the Office of Thrift Supervision. In 2013 the OCC released "Risk Management Guidance,"a bulletin which establishes risk management guidelines, relating to third party management, for national banks.

All national US banks and federal savings institutions, and federal branches and agencies of foreign banks.

OCC Third Party Relationships-Risk Management

http://en.wikipedia.org/wiki/Office_of_the_Comptroller_of_the_Currency