Fratricide is the act of a person killing his or her brother or sister. The word fratricide derives from the Latin word frater (meaning: "brother").

Compare with child murder (the killing of an unrelated child), infanticide (systematic killings of a large number of children), filicide (the killing of a child by his or her parent), and patricide (the killing of a parent by his or her child).

The word is also used in a military context to refer to friendly fire incidents.

Fratricides in literature

• Cain kills his brother Abel in the Book of Genesis.
• Medea killed her brother Apsyrtus (Greek myth)
• Michael Corleone (in The Godfather, Part II) has his brother Fredo shot.
• Romulus killed Remus, the twin brother who built the Roman Empire with him.