black hat
noun
1
in a drama, or in life viewed as a drama, the villain US, 1964.
2
a computer hacker with no honourable purpose. Sometimes embellished to 'black hat hacker' US, 2001.
3
a member of Pathfinder platoon, dropped behind enemy lines to make deep reconnaissance patrols and to establish landing zones for the initial helicopter waves US, 1982.
4
a US Army drill instructor US, 1986