Plausible deniability is the ability of people, typically senior officials in a formal or informal chain of command, to deny knowledge of or responsibility for actions committed by members of their organizational hierarchy. They may do so because of a lack or absence of evidence that can confirm their participation, even if they were personally involved in or at least willfully ignorant of the actions. If illegal or otherwise disreputable and unpopular activities become public, high-ranking officials may deny any awareness of such acts to insulate themselves and shift the blame onto the agents who carried out the acts, as they are confident that their doubters will be unable to prove otherwise. The lack of evidence to the contrary ostensibly makes the denial plausible (credible), but sometimes, it makes any accusations only unactionable.

The term typically implies forethought, such as intentionally setting up the conditions for the plausible avoidance of responsibility for one's future actions or knowledge. In some organizations, legal doctrines such as command responsibility exist to hold major parties responsible for the actions of subordinates who are involved in actions and nullify any legal protection that their denial of involvement would carry.

In politics and espionage, deniability refers to the ability of a powerful player or intelligence agency to pass the buck and to avoid blowback by secretly arranging for an action to be taken on its behalf by a third party that is ostensibly unconnected with the major player. In political campaigns, plausible deniability enables candidates to stay clean and denounce third-party advertisements that use unethical approaches or potentially libelous innuendo.

Although plausible deniability has existed throughout history, the term was coined by the CIA in the early 1960s to describe the withholding of information from senior officials to protect them from repercussions if illegal or unpopular activities became public knowledge.