A criminal accomplice is a person who knowingly, voluntarily, or intentionally assists another person in the commission of a crime—or under some circumstances, a person who fails to prevent another person from committing a crime. Unlike a person who aids and abets a crime by helping with the planning of the crime but is often not present at the scene of the crime—and unlike an accessory after the fact, who is not present at the scene of the crime but assists after the commission of the crime to help the perpetrator avoid arrest or punishment—an accomplice actively participates in the commission of the crime. For example, a person who acts as a lookout or getaway driver for a bank robbery is an accomplice.

In many states the traditional distinctions between the culpability of accomplices and principals to a crime have been replaced by statute—including the felony murder rule that may make an accomplice guilty of first degree or capital murder if he was the lookout or getaway driver for a bank robbery that resulted in a death.

In Nevada, an individual who assists in the commission of a crime is considered an accomplice and can be charged and punished as if they had committed the crime themselves. Nevada law does not strictly differentiate between principals and accomplices; both are subject to the same legal consequences. This means that someone acting as a lookout or getaway driver during a crime, such as a bank robbery, can be charged with the same offenses as the person who directly commits the criminal act. Furthermore, under Nevada's felony murder rule, an accomplice can be found guilty of first-degree murder if a death occurs during the commission of certain felonies, even if the accomplice's role was limited to assistance rather than directly causing the death. This reflects the state's stance on holding all participants in a crime responsible for the outcomes of the criminal activity, regardless of their specific role.