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The Five Black Dwarfs were suspicious and rather aggressive Black Dwarfs, who lived in a cave near the Seven Brothers of Shuddering Wood during the Narnian Revolution.

Unlike the Red Dwarfs, however, the Black Dwarfs do not seem to be brothers. They define their allegiance to Caspian X negatively, as they will support him if he is against Miraz, but not because he is for Old Narnia.

They appear to be more sinister than the Red Dwarfs, as evidenced by their wish to call for the help of Ogres and Hags, which were once the most faithful of followers to the White Witch.

"There's an Ogre or two and a Hag that we could introduce you to, up there."
"Certainly not.
―Eldest Black Dwarf and Caspian (Chapter 6) [src]

Three Black Dwarfs attended the Great Council, and were sent to investigate the intruder (who turned out to be Doctor Cornelius) with their bows and arrows.

One of the Dwarfs was ready to kill anyone if he had to.