Capital punishment, also known as the death penalty and formerly called judicial homicide, is the state-sanctioned practice of deliberately killing a person as a punishment for an actual or supposed crime, usually following an authorized, rule-governed process to conclude that the person is responsible for violating norms that warrant said punishment. The sentence ordering that an offender be punished in such a manner is known as a death sentence, and the act of carrying out the sentence is known as an execution. A prisoner who has been sentenced to death and awaits execution is condemned and is commonly referred to as being "on death row".

Crimes that are punishable by death are known as capital crimes, capital offences, or capital felonies, and vary depending on the jurisdiction, but commonly include serious crimes against the person, such as murder, mass murder, aggravated cases of rape (often including child sexual abuse), terrorism, aircraft hijacking, war crimes, crimes against humanity, and genocide, along with crimes against the state such as attempting to overthrow government, treason, espionage, sedition, and piracy. Also, in some cases, acts of recidivism, aggravated robbery, and kidnapping, in addition to drug trafficking, drug dealing, and drug possession, are capital crimes or enhancements. However, states have also imposed punitive executions, for an expansive range of conduct, for political or religious beliefs and practices, for a status beyond one's control, or without employing any significant due process procedures. Judicial murder is the intentional and premeditated killing of an innocent person by means of capital punishment. For example, the executions following the show trials in Russia during the Great Purge of 1937–1938 were an instrument of political repression.

Etymologically, the term capital (lit. "of the head", derived via the Latin capitalis from caput, "head") refers to execution by beheading, but executions are carried out by many methods, including hanging, shooting, lethal injection, stoning, electrocution, and gassing.

As of the end of 2022, 53 countries retain capital punishment, 111 countries have completely abolished it de jure for all crimes, seven have abolished it for ordinary crimes (while maintaining it for special circumstances such as war crimes), and 24 are abolitionist in practice. Although the majority of nations have abolished capital punishment, over 60% of the world's population live in countries where the death penalty is retained, such as China, India, the United States, Singapore, Indonesia, Pakistan, Bangladesh, Nigeria, Egypt, Saudi Arabia, Iran, Japan, and Taiwan.

Capital punishment is controversial in several countries and states, and positions can vary within a single political ideology or cultural region. Amnesty International declares that the death penalty breaches human rights, stating "the right to life and the right to live free from torture or cruel, inhuman or degrading treatment or punishment." These rights are protected under the Universal Declaration of Human Rights, adopted by the United Nations in 1948. In the European Union (EU), Article 2 of the Charter of Fundamental Rights of the European Union prohibits the use of capital punishment. The Council of Europe, which has 46 member states, has sought to abolish the use of the death penalty by its members absolutely, through Protocol 13 of the European Convention on Human Rights. However, this only affects those member states which have signed and ratified it, and they do not include Armenia and Azerbaijan. The United Nations General Assembly has adopted, throughout the years from 2007 to 2020, eight non-binding resolutions calling for a global moratorium on executions, with a view to eventual abolition.