i actually had a tiefling npc in my campaign.

Captain Thaddius

He's got quite the story to him which I'll link here:
"So my little brother was/is desperate for me to finally draw a portrait of one of his NPCs from the last 2 year story that he DMed for. So I settled on drawing Thaddius our Ship Captain that my character and her party rescued from slavery. He basically went through hell with us and nearly died but we fought over who would die in his place. This NPC I would never be able to summarize in a word, for one he married one of our players and had a child with her through the course of the story. And some how he found his way into every player's memories as the awesome guy we could always trust and depend on to get our flag ship where it had to be. He might not have been a noble but the guy certainly was a hero."

sauce for quote:
mercuryashoke.deviantart.com/art/Captain-Thaddius-565287731