The death penalty—also known as capital punishment—refers to the process of state and federal courts sentencing persons convicted of the most serious criminal offenses (capital offenses or capital crimes) to death. The specific crimes and circumstances for which the death penalty is a potential punishment (usually murder) are defined by state and federal statutes enacted by state legislatures and the United States Congress, respectively.

These death penalty or capital punishment statutes are often located in the penal or criminal code, and often in the same statute that defines a criminal offense such as murder. Twenty-two states and the District of Columbia do not have the death penalty as a potential punishment for any criminal offense.

In Missouri, the death penalty is a legal form of punishment for certain capital offenses, primarily first-degree murder under specific circumstances that are considered aggravating factors. These aggravating factors can include previous convictions for violent crimes, murder committed during another felony, murder of a law enforcement officer, or multiple murders, among others. The statutes governing capital punishment in Missouri are found in the Missouri Revised Statutes, specifically in Chapter 565 concerning offenses against the person. The decision to seek the death penalty is at the discretion of the prosecuting attorney and the sentence is determined by a judge or jury following a conviction. Missouri's methods of execution have included lethal injection and gas, with lethal injection being the primary method used in recent years. It's important to note that while Missouri does have the death penalty, the application of capital punishment is subject to ongoing legal and public debate, and procedures are governed by both state law and applicable federal constitutional standards.