Margie Velma Barfield (ne Bullard; October 29, 1932 November 2, 1984) was an American serial killer who was convicted of one murder, but who eventually confessed to six murders in total. Barfield was the first woman in the United States to be executed after the 1976 resumption of capital punishment and the first since 1962. She was also the first woman to be executed by lethal injection.

Capital punishment, also known as the death penalty, is a state-sanctioned practice of killing a person as a punishment for a crime. The sentence ordering that an offender is to 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, among other crimes. 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.

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.

Fifty-four countries retain capital punishment, 107 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 27 are abolitionist in practice. Although most 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, parts of the United States, 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. 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 47 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, Russia, 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.