Coppertops

The Matrix is one of the special encounters in Fallout Tactics: Brotherhood of Steel.

After the robot menace has been revealed the character can come across a building being guarded by several of the robots. The robots will not be hostile, but are in fact guarding a facility where humans are running on treadmills. Lockers next to the treadmills contain Small Energy Cells and are presumably replenished.

This is thought to be a reference to the popular movie "The Matrix".