Manslaughter is the unlawful killing or homicide of a human being without the premeditation or malice (malice aforethought) required for the criminal offense of murder.

Many states have two types of manslaughter: (1) voluntary manslaughter—the defendant intended to kill the victim, but did so in self-defense, or in the heat of passion and without premeditation, or the defendant was insane and did not understand that the killing was wrong; and (2) involuntary manslaughter—the defendant negligently or recklessly caused the death of another person—such as when a person is intoxicated while operating a motor vehicle and causes an accident that results in the death of another person.

Some states do not have separate criminal offenses for voluntary and involuntary manslaughter—these states may have the offense of manslaughter and identify certain aggravating factors that may enhance the penalties upon a conviction for manslaughter.

Manslaughter is a felony offense and may be punished by a lengthy prison term. Manslaughter laws are generally located in a state's statutes—often in the penal or criminal code.

In Nevada, manslaughter is categorized under NRS 200.040 and NRS 200.050, distinguishing between voluntary and involuntary manslaughter. Voluntary manslaughter (NRS 200.050) is defined as an unlawful killing without malice and upon a sudden heat of passion caused by a provocation sufficient to incite an average person. It is considered a lesser offense than murder due to the absence of premeditation. Involuntary manslaughter (NRS 200.070), on the other hand, involves the unintentional killing of another person through a negligent or reckless act, such as a fatal accident caused by drunk driving. Both types of manslaughter are felonies in Nevada. Voluntary manslaughter is punishable by 1 to 10 years in Nevada state prison, while involuntary manslaughter carries a sentence of 1 to 4 years and/or a fine up to $5,000. The specific circumstances of the offense can influence the severity of the punishment.