This mod flags named Slog NPCs (Wiseman, Deirdre, Arlen Glass, Jones, Holly) as Essential, which makes them unable to accidentally die. (Helpful for all those random raider attacks.)

Also includes an option to flag all of them as Protected. (Protected NPC's can only be killed by the player.)

See also:
Essential Vault-Tec Rep
Essential Abernathy(s)
Essential Named Settlers (incoming)