Fourth-degree droid (Earth-2042)

A fourth-degree or class four droid is a droid programmed for military and security purposes. Such droids tended to perform tasks wherein violence or combat might be expected. Class four droids were grouped into four major categories: security droids, which are used to guard locations; battle droids, which are the most common variety and used in standard combat; and assassin droids, the only variety expressly designed to kill organics.

Source

 * https://starwars.fandom.com/wiki/Fourth-degree_droid