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In many states the traditional distinctions between the culpability of accomplices and principals to a crime have been replaced by statute—including the felony murder rule that may make an accomplice guilty of first degree or capital murder if he was the lookout or getaway driver for a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 New York State, the concept of a criminal accomplice is covered under the New York Penal Law. An individual who acts as an accomplice is typically charged with the same degree of the crime as the principal actor. This is because New York law follows the theory of 'accomplice liability,' which holds that anyone who intentionally aids, commands, induces, or otherwise participates in the commission or attempted commission of a crime can be held criminally liable as an accomplice. For example, a lookout or getaway driver in a bank robbery can be charged with robbery to the same extent as the person who actually commits the robbery. Furthermore, under certain circumstances, such as when a death occurs during the commission of a felony, accomplices can also be charged with felony murder, which is a serious offense that can result in severe penalties, including life imprisonment or even the death penalty under federal law if applicable. It's important to note that the specific charges and potential penalties can vary depending on the details of the crime and the degree of the individual's involvement.