"Have you ever been in the situation that you’re supposed to speak to a NPC, and you can see lots of other NPC’s, just not this particular one? Try this:

/tar NPCname

It will show up on your radar! If that still doesn't help you find them, right click their portrait and put a nice bright raid target on them. The icon will show up even if there's something between you and them."

Submitted by: Agamemnon