Arc Pylons are a government-utilized, offensive technology in Dishonored. They use whale oil to power the pylons, meaning these weapons can be disabled if Corvo Attano pulls the oil tank out of the power module. They work similarly to Walls of Light but are effective at a distance, electrocuting anything within range that they have not been configured to recognize (for instance, members of the Watch or allies to the Lord Regent will be safe from the pylons). They can be hacked by Corvo to ignore him and turn against the Watch instead.
The arc pylons are the brainchild of Anton Sokolov. The Arc Pylon was later adapted by Piero Joplin to be much more powerful and have a much greater range. He also adapted it in cooperation with Sokolov to be able to incapacitate all enemies around the pylon instead of killing them. This can be used to great effect during the mission, The Loyalists, to eliminate all of the guards in the mission area while remaining undetected, making the mission much easier to complete.