Sneering Imperialist

Sneering Imperialist is a perk

Effects
Sneering Imperialist provides a 15% damage boost and a 1.25x multiplier to the player character's V.A.T.S. chance-to-hit when attacking members of certain groups, such as tribals, raiders, Fiends, and Great Khans.

Although the perk's description only mentions raiders, junkies, and Zion's various tribals, which non-player characters the perk affects are actually determined by the non-player character's "race" (referring to a game-specific setting rather than perceived racial makeup). This covers a number of groups/factions in their entirety:

In addition, a number of other groups are partially composed of members of the specified race designations:
 * Freeside squatters
 * Great Khans
 * Refugees
 * Wastelanders

Finally, a few named non-player characters are covered by this perk:

Behind the scenes
According to Joshua Sawyer, the perk's icon was created by Brian Menze, who took inspiration for it from the Sharpe novels by Bernard Cornwell.