The mens rea for murder is defined as malice aforethought, which has come to mean either an intention to kill or an intention to cause grievous bodily harm.

The common-law designation of murder mens rea; covers a wide range of mental states.

(law) criminal intent; the thoughts and intentions behind a wrongful act (including knowledge that the act is illegal); often at issue in murder trials

A state of mind requirement for murder. It is either an intent to kill or an intent to do an extremely dangerous act with a conscious disregard for the consequences.

Mental state required to prove murder.

Malice Aforethought is a 1931 murder mystery novel written by Anthony Berkeley Cox, using the name Francis Iles. It involves a Devon physician who slowly poisons his domineering wife to death so he may be with the woman he loves. The novel is a groundbreaking work in that it was the first in the genre to reveal the murderer's identity at the beginning of the story and grant the reader insight into the workings of a criminal mind.

Specifically in the criminal law, malice aforethought is the element of mens rea (Latin for "guilty mind") which must accompany the actus reus of death, in order to secure a conviction for murder under the common law.