This question has a few possible interpretations depending on which mythology we're talking about. Let's explore the most likely scenarios:
1. Norse Mythology:
In Norse mythology, Loki's father is Farbauti, a giant. Farbauti is not known to have been killed by anyone in the myths. He is simply a character who appears in the family tree of Loki.
2. Marvel Cinematic Universe (MCU):
In the MCU, Loki's adoptive father is Odin, the Allfather of Asgard. However, Odin is not killed by anyone in the MCU. He is shown to be aging and eventually dies of old age.
3. Other Interpretations:
It's possible that you are referring to a different version of Loki, or a different myth altogether. If you could provide more context, I could give you a more specific answer.
Conclusion:
Based on the most common interpretations of Loki's father, there is no known character who killed him.