"There are beings in the universe billions of years older than any of our races. They walked among the stars like giants, vast, timeless. They created great empires, taught the new races, explored beyond the rim. The oldest of the ancients are the Shadows. We have no other name for them."
- Delenn: "Matters of Honor"
The Shadows have fought the First Ones since the beginning of time. A thousand years before the construction of Babylon 5, they were defeated in a Great War by a coalition including the Vorlons, other First Ones and the Minbari. They then went into hibernation, on their homeworld of Z'ha'dum to resume battle in the mid 23rd century. The Shadows are four-legged, spidery creatures. They cannot be seen by Humans and most aliens, because the creatures are beyond their normal range of perception. The Shadows use bio-organic technology, and their vessels have a powerful beam that can easily slice through other ships.
Shadow vessels are all black with a shimmering skin, and resemble a spider. Shadow vessels require a living being for their central operating systems. The Shadows also use smaller Scout and Fighting ships. The Shadows believe in evolution through conflict. They prefer to work behind the scenes and manipulate others into fighting and destroying their enemies, rather than joining the battle themselves. At the end of the Shadow War, the Shadows departed beyond the Rim, together with the Vorlons, the First Ones, and Lorien, the original First One.