"And Ye Shall Know The Truth And The Truth Shall Make You Free."
—John 8:32, The CIA motto.
How do you know the CIA wasn't involved in the Kennedy assassination?
Central Intelligence Agency... The Agency.
After World War II, the OSS was disbanded. With the onset of the Cold War, it was decided that a new intelligence agency was needed. The name "Central" reflects that it was originally supposed to be a clearinghouse among various other agencies. However, it became effectively a new OSS and acquired many veterans from that previous service.
The CIA has been controversial, having at times been accused of incompetence (see the second page quote), immoral actions, or both. In some fictional portrayals, they are often regarded as being The Men in Black. This portrayal, at least, is an exaggeration, as if the CIA was really that skillful, we might ask why it took us so long to win the Cold War. Of course, maybe that's what they wanted.
Nonetheless, the CIA has had its successes. For instance, a large part of the reason for the United States succeeding in the gigantic Death Glare contest during the Cuban Missile Crises was that America had a mole telling the U.S. government that the Soviets had less capacity than they claimed.
The typical depiction of the CIA in both fiction and the more speculative forms of conspiracy theory, usually portrays them as being somewhere between spies and assassins, as well as at times being allegedly responsible for the overthrow of anti-American foreign governments. Liam Neeson's portrayal of a possible former CIA man in Taken is very standard, as is Harrison Ford's portrayal in Patriot Games. The Agency's adventures in Nicaragua, among other places, can also make for particularly interesting reading; as can Peter Joseph's interview with John Perkins. It is at times implied that they are additionally a research organisation of sorts, with an interest in experimental tactics that would usually be considered impossible by the mainstream public. (Such as MK-Ultra, the Psychic Warrior program(s), etc)
Although it says "The Agency" up top here, actual CIA employees (and those in the know) tend to call it "The Company;" calling it "The Agency" is acceptable, but calling it "The CIA" in anything except perhaps first reference is grounds for getting Gannon Banned. Other federal government types might call it the "Other Government Agencies" (OGA), typically when its involvement in something or other is an Open Secret. In exceptionally double-cross-intensive stories you might see "The Company" and "The Agency" used to represent different factions of the CIA.
A lot of fiction has references to the CIA. Here are just some.
- The Blackford Oakes Series by William F. Buckley is a series of tales about the adventures of the CIA operative Blackford Oakes.
- Much of Tom Clancy's work, including The Hunt for Red October.
- The Bourne series
- The Assignment series (every book has the word assignment in the title), features CIA agent Sam Durell.
- John Wells series.
- NCIS: Los Angeles.
- The Company
- Burn Notice: Doesn't actually show up terribly often, but agents do show up from time to time. Michael Westen himself was most likely a CIA agent under unofficial cover until he was burned, and one of his main reasons for wanting to get un-burned is to get back with the Company.
- Season 4 has Michel working for the CIA again, and he manages to persuade a soldier to join the CIA after having previously refusing to join.
- Covert Affairs: Actually set at a rather fictionalized version of the CIA.
- The Agency
- Modern Warfare 2. They only appear on one level but that level probably was enough.
- Naturally, they play a much more prominent role in Black Ops, including a main playable character who is a CIA agent.
- They get a mention in Alpha Protocol, though the main group is a Government Agency of Fiction.
- The CIA is heavily featured in the Big Boss prequels of the Metal Gear Solid series. Metal Gear Solid 3 showcases Big Boss's time as a CIA agent and his eventual deserting of the organization as a protest towards its corruption, MPO and Peace Walker showcase the CIA trying to get Big Boss back on their side and when he refuses conspiracies abound.