Barb wire

Barb wire is a metal fencing material used to deter tresspassers from encroaching upon or exiting a secured area. Barb wire is an interconnecting lattice of sturdy wire with sharpened points positioned at measured intervals that can easily ensnare clothing or rend flesh. Farmers use barb wire to corral livestock. Prisons will arrange rolls of barb wire along the top edges of prison walls and other facilities including local and national government areas may utilize it to ward off tresspassers.

In fiction
In the Dean Koontz novel Hideaway, as well as the feature film adaptation, Satanic murderer Vassago created elaborate and macabre pieces of artwork out of various materials, including barb wire.

In the Saw film series, the John Kramer, aka, the Jigsaw Killer created a barb wire trap which he used on a victim named Paul Leahy. Paul awakened nearly naked inside of a cage filled with barb wire and was expected to claw his way through it to gain his freedom. Unfortunately for Paul, he was unable to reach the exit before succumbing to his injuries. (Saw (2004)