The only time I have ever "cheated" for an NPC would be by reloading. I don't know if that quite qualifies under the OP's intention, but there you have it.
Once was for a quest NPC that you have to go into an Oblivion gate to rescue (don't recall the name - spoilers and whatnot, anyway), and when I got him, he got knocked off a bridge into lava. Since he was essential, kept dying and coming back to life in the lava, like some horrible Daedric torture victim. I ended up having to reload to a recent save for that one - though I probably could have better used the console then.
Another time was when I found poor Quill-Weave dead on the road somewhere between Imperial City and Anvil. No Oblivion gate or obvious killer in sight. At the time, I had just recently heard that Robert Jordan (Author of the Wheel of Time books) had passed away. I thought "NO! I can't let another writer die before finishing their works!" So I reloaded until I found a game where she was still alive. It wasn't too bad, cause I think I just had to go a couple games back. After that day, I made sure to visit her every time I was in Anvil (if she was home).