Perseus the myth

Perseus accidentally killed his grandfather, as the prophecy had said before he was born. But you're right, Perseus wasn't a failure. I don't think Jason, Theseus or Achilles were considered failures either, even though I don't like some things, which these heroes did according to the legends. So I guess it's like you said, that Disney just pulled the names of their ass, not thinking about how inaccurate they were.

Intelligence and purity.

While he was at the Olympic games while throwing the discus he slipped and killed Acrisius, his grandfather. Also after completing the more famous part of his adventure Perseus had a tendency to misuse Medusa's head turning anyone he came across into stone and making himself a massive pain in the @$$... though at least Atlas will never drop the sky.

"The game's afoot!"

Perseus was supposed to live a long life. He had a long history of family feuding that finally caught up to him in the end when he was assassinated by his cousin Megapenthes, who was the son of Perseus' grandfather's twin brother, who he kicked out of his kingdom of Argos. Megapenthes and his father ended up ruling over Tiryns, and after Perseus had accidentally killed his grandfather, he first inherited Argos, and then traded the throne of Argos for Tiryns on account of the guilt he had for the manslaughter. Megapenthes probably considered Argos to be his by right, anyways, so it was a win-win deal. Perseus raised his family in Tiryns, and the ruling title was first passed to his son Electryon, then his other son Sthenelus. It's not too clear when Perseus was killed by Megapenthes during the latter events.