The Grim Reaper

The Grim Reaper is the personification of death. The Reaper is a skeleton with a black robe and usually has a scythe. The scythe, which was used for farming when the Grim Reaper was first thought of, shows how the Grim Reaper reaps human souls. The Grim Reaper was originally thought of in the 14th century during the Black Death, which was a deadly pandemic. This imagery is most likely a result of the Black Death and had remained a staple in Halloween costumes and media for centuries.

Sources:

Britannica
Abigail Owen