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 Texas, manslaughter is considered a second-degree felony under Texas Penal Code Section 19.04. The state distinguishes between manslaughter and murder based on the absence of premeditation and malice aforethought. Manslaughter in Texas typically refers to what other jurisdictions might call 'involuntary manslaughter,' where a person recklessly causes the death of another individual. An example is causing a fatal accident while driving under the influence of alcohol or drugs. Texas does not use the term 'voluntary manslaughter,' but it does have a similar concept called 'provoked' or 'heat of passion' killings, which are addressed under the murder statute (Section 19.02) as a potential mitigating circumstance that can reduce a murder charge to a second-degree felony. Penalties for manslaughter in Texas can include imprisonment for 2 to 20 years and a fine of up to $10,000. Aggravating factors, such as the use of a deadly weapon, can influence the severity of the sentence within the statutory range.