Glowing One (trait)

Glowing One is a Fallout Tactics trait, available only to ghouls. It symbolizes them being the eponymous "Glowing Ones", even though the characters don't visibly glow in-game.

Extreme radiation exposure has left you glowing in the dark! Darkness is no obstacle to you or your enemies. You gain resistance to radiation but you radiate those around you.

Behind the scenes
The Glowing One trait is the only stats that is not represented by the Vault Boy in the Pip-Boy of all Fallout games, it has no image, probably due to an oversight of the developers.