Diablo is a town that acts as the home base and starting point for adventurers in John Nelson's Knight Quest game system, equivalent to the city of Evenhold in Eamon, and is the setting for the system's first adventure, Amateur Alley. Nelson describes Diablo as a "rough frontier town where a man's best friend is his sword."
Places of interest near the town square in Diablo include:
- The inn operated by Pedro Gonzales where adventurers may rent rooms;
- The bank operated by Waldo Farnby with assistance from a notary public;
- The armoury, owned by Angelo Carvetti who sells weapons and armor;
- "Ye Olde Magicks Shoppe", operated by the venerable old wizard Abbra Kadabra who teaches adventurers new spells or removes existing ones from their memory;
- The general store operated by Vance Whipple who both buys and sells merchandise;
- The gymnasium where adventurers may take training from an ogre named Oggie Groddie in the areas of language, fitness, or combat.
Those leaving town for adventure follow the long dusty trail that heads west out of Diablo.