I just remembered that he likely killed a number of fire demons in Hel, but not like that was a bad thing, and so did his brothers. And of course he "killed" Thor there as well in order to get him to Valhalla, but... it was Thor's idea, Loki had to be talked into it, and it was not for realsies, so....
But yeah, can't think of anyone human or Asgardian, except the possible collateral damage deaths mentioned before, but no one like, specific. I mean, he stabbed Freyja, but I think it was clear that his intent was to put her in a coma, not kill her. Which is not great, I will admit, but... I think the closest was when he pushed the Elf Queen off that balcony, at Malekith's insistence, but Jane saved her.