She was introduced along-side her counterpart, Hawkman.
Her story begins when she mets Hawkman, aka Archaeologist Carter Hall, who had a dream he was an ancient Egyptian prince, Khufu, whose lover was named Shiera, or Chay-Ara. The next day Carter met Shiera. This lead to them becoming romantically involved.
Shiera is said to be the reincarnation of the Princess Chay-Ara.
The prince and princess were said to have been killed by Hath-Set with a knife forged from Nth metal. The properties of the metal and the strength of their love created a bond that allowed them to be reborn multiple times throughout the centuries.
Shiera didn’t actually wear the Hawkgirl costume, or be recognized as Hawkgirl until July of 1941 in All-Star Comics #5.
She was a member of the All-Star Squadron, and often helped the Justice Society of America.
Shiera and Carter had a son. However, Shiera died when she was merged with Carter and Kator Hol to form a new version of Hawkman known as “hawk god.”
She was revived during the events of Blackest Night by the White Lantern ring.