Nostalrius Begins - Quality wow vanilla realm (1.12)

Franclorn Forgewright the NPC who gives a Blackrock Depths quest, should only be seen while dead, but as of right now, he is invisible while dead, and you can take his quest while alive.

The NPC Gaeriyan who you talk with on the Linken quest chain north of Tanaris GY is sort of the same, you can talk to him while alive & although you can see him while dead the quest will not work.