Guardian Brotherhood

 The Guardian Brotherhood is a group that is described as being on "barely tolerant terms" with the Brotherhood of Steel in The Armageddon Rag, Vol. 3. 

Appearances
The Guardian Brotherhood appears in The Armageddon Rag, Vol. 3. They would have likely appeared in Interplay's orginal Project V13, also known as Fallout Online. This project has been cancelled in favour of a new, unrelated, Project V13.