The Heretic's Brand refers to both a dire punishment leveled on an Overseer, and the tool used to administer said punishment.
The brand is a punishment only applicable to members of the Abbey, including the High Overseer himself. The sentence is only given to someone who has committed a great wrong in failing to abide by the Seven Strictures of the Abbey of the Everyman, but has not committed a civil crime. It is a minor criminal offense to offer aid, shelter, or solace to anyone who bears the brand.
- An Overseer being sentenced to receive the Heretic's Brand is a rare occurrence, indicating the seriousness of the offense necessary to incur it.
- It is not clear who, if anyone, has the authority to use the Heretic's Brand and what procedures have to be followed to sentence them to receive it. However, it is implied that when someone receives the brand, no one questions why they received it, and they are automatically ostracized. Even if Corvo is seen breaking to the Abbey and killing overseers before branding Campbell, the High Overseer is automatically cast out of the Abbey.
- An Oracular Sister named Romana Kyme was branded and banished from the Abbey after being wrongfully convicted of apostasy, though despite this injustice she chose to accept the branding instead of The Outsider's offer of his Mark. 
- According to the book On Branding Heretics, not only is the metal instrument heated, but an unnamed chemical compound is also involved as well that acts immediately to scar those that are branded.
- Corvo Attano can use the brand to eliminate Thaddeus Campbell non-lethally during the High Overseer Campbell mission. Afterwards, Campbell can be found as a weeper, still with his Brand.
- Campbell mentions his intent to use the Heretic's Brand against "undesirables", including Hiram Burrows. However, as the brand can only be used on members of the Abbey, it is unknown how he meant to accomplish this task.
- The brand loosely resembles the logo from the 1994 game Heretic, as depicted here and here.