Ghoulish/Fallout 4

Ghoulish is a perk in Fallout 4.

Effects
The player can regenerate lost health from latent radiation just like a Ghoul without actually being a ghoul. The health regeneration rate increases with every rank, and on the third rank, feral ghouls can randomly become friendly toward the player.

The fourth rank added by Nuka-World adds another benefit, slowly reducing the radiation count over time and restoring health.