The Trojan War
During the Trojan War, Diomedes fought with Hector and saw Ares fighting on the Trojans' side. Diomedes called for his soldiers to fall back slowly. Hera, Ares' mother, saw Ares' interference and asked Zeus, Ares' father, for permission to drive Ares away from the battlefield. Hera encouraged Diomedes to attack Ares and he threw his spear at the god. Athena drove the spear into Ares' body and he bellowed in pain and fled to Mt. Olympus, forcing the Trojans to fall back.
Hera hated Pelias for having murdered Sidero, his step-grandmother, in a temple to Hera. She later attempted to manipulate Jason and Medea to kill Pelias and succeeded.
Hera, with Zeus, turned King Haemus and Queen Rhodope into mountains (Mt. Balkan and Mt. Despoto, respectively) for their vanity.