The Book Of Quirk Malfunctions!

1 (Izuku Midoriya)

Midoriya is in a fight with a villain of some sort, and he decides to use 100% of his power, but his quirk goes beyond it's limit, causing him to shatter all of his bones, including his skull. The villain realizes this and decides to put Midoriya out of his misery, and stomps on his head, causing it to explode into blood, bone shards, and brains, and his eyes roll over to the feet of perhaps Uraraka or Todoroki, who came to help him out, but were too late to save him.