Fratricide is the act of killing one's own brother.
The Fratricide (1897) by Akseli Gallen-Kallela, illustrating the poem The Brother Murderer from Kanteletar
In the biblical Book of Genesis, Cain and Abel are the first two sons of Adam and Eve. Cain, the firstborn, was a farmer, and his brother Abel was a shepherd. The brothers made sacrifices, each from his own fields, to God. God regarded Abel's offering, but not Cain's. Cain killed Abel and God cursed Cain, sentencing him to a life of transience. Cain then dwelt in the land of Nod, where he built a city and fathered the line of descendants beginning with Enoch.
Cain slaying Abel, by Peter Paul Rubens, c. 1600
Cain leadeth Abel to death, by James Tissot, c. 1900
A depiction of Cain burying Abel from an illuminated manuscript version of Stories of the Prophets
Cain and Abel. Plaster cast after bronze (1425–1438) by Jacopo Della Quercia (1374–1438), Bologna, Italy. National Museum of Scotland, Edinburgh