The Supreme Court and the federal court system
The reality is that the Executive Branch alone consists of 15 major (cabinet level) departments, over 65 "Independent Agencies & Government Corporations" almost 500 Presidential staff, 1,115 "Executive Advisory Boards, Commissions & Committees", 1046 "Advisory Committees" and several "Government-Sponsored Entities" (GSEs).
The government website USA.GOV publishes organizational charts for many federal departments but the charts are spread over a bewildering array of web pages accessible by links that are often not obvious. This site displays the bulk of the organizational structure of many of these agencies in one place in order to convey a better idea of just how large America's federal bureaucracy has become.
The 15 cabinet level departments and the Independent Agencies & Government Corporations are listed in the panel to the right.
Each of the 15 cabinet-level departments (plus EPA,GSA & GAO) link to a two page view that more completely presents the size of their bureaucratic structure.
Information about America's Quasi Government - the GSEs - can be found on this page.
Here are links for Presidential staff, Independent Agencies and Government Corporations, and Federal Advisory Committees by Agency (select "All Agencies" as the search term).
NOTE: The best collection of federal $DATA$ on the web can be found at usgovernmentspending.com