Hippomenes in The Story of Atalanta
Hippomenes is the sneaky dude who manages to beat Atalanta in a foot race by tossing golden apples on the ground. No, she doesn't trip on them or something; for some reason, she can't help but stop and pick them up. (Which is weird, but whatever.) Not only does Hippomenes mess up Atalanta's undefeated running streak, he also totally messes up her whole life. When he forgets to thanks Aphrodite for lending him those pesky golden apples, the goddess of love punishes him by inflicting him with a bad case of lust. This causes him to get it on with Atalanta in a temple of Zeus (or Cybele in some versions), and as punishment both he and his unlucky wife are turned into lions. So yeah, for Atalanta, Hippomenes was seriously bad news.