A secret trial is a trial that is not open to the public, nor reported in the news. Generally no official record of the case or the judge's verdict is made available. Often there is no indictment, the accused is not able to obtain the counsel of an attorney or confront witnesses for the prosecution, and the proceedings are characterized by a perceived miscarriage of justice to the benefit of the ruling powers of the society.

In the English-speaking world, one of the most notorious secret courts was the Star Chamber as it was used under Charles I in the early 17th century. The abuses of the Star Chamber were one of the rallying points of the opposition that organized around Oliver Cromwell, and ultimately resulted in the execution of the deposed king. The term "star chamber" became a generalized term for a court that was accountable to no one (except the chief executive) and was used to suppress political dissent or eliminate the enemies of the regime.

Secret trials have been a characteristic of almost every dictatorship of the modern era. Although the Great Purges in the Soviet Union under Joseph Stalin are best remembered for the Moscow Trials, show trials in which the court became a parody of justice, most of the victims of the Terror were tried in secret. Mikhail Tukhachevsky and his fellow Red Army officers were tried in secret by a military tribunal, and their executions were announced only after the fact. The presiding judge of the Moscow Trials, Vasili Ulrikh, also presided over large numbers of secret trials lasting only a few minutes, in which he would quickly speak his way through a pre-formulated charge and verdict.

In the United States, there have been concerns that the USA PATRIOT Act passed following the September 11 terrorist attacks could be used to authorize secret trials and generally eliminate the due process protections which are guaranteed under the US Constitution.

Mordechai Vanunu was famously subject to a secret trial in Israel, having been kidnapped and deported from Italy by the country's secret police.