Hawk Girl

The Golden Age Hawkgirl was Shiera Sanders Hall, the reincarnation of the Egyptian princess Chay-Ara, and partner of Carter Hall, the Golden Age Hawkman. Centuries ago, Chay-Ara and her lover Prince Khufu were killed by Hath-Set with a knife forged from Nth metal. The properties of the metal and the strength of the duo's love created a bond between them, causing them to be reborn multiple times throughout the centuries.

In the early 20th century, Chay-Ara was reborn as Shiera Sanders. She was kidnapped by Dr. Anton Hastor (reincarnation of Hath-Set), but subsequently rescued by Hawkman (her reborn lover Khufu). Shiera became the hero's frequent ally and love interest. Eventually, she was granted a costume of her own and a belt of gravity-defying Nth metal, and joined him at his side as Hawkgirl.

The Hawks were members of the All-Star Squadron, and while Hawkman was a member of the Justice Society of America, Hawkgirl was not, only assisting the group on occasion. Recent retcons seem to point to Hawkgirl being formally inducted into the JSA at some time, however. Eventually, Carter and Shiera married and had one son, Hector Hall, the previous Doctor Fate.
Through retcon Carter and Shiera also joined the Justice League of America in the late 1980s, serving as liaisons between that group and the Justice Society.
Shiera died when she was merged with Carter and Katar Hol to form a new Hawkman version, a "hawk god" creature, during the events of Zero Hour, but was revived during the events of Blackest Night by the White Lantern ring.

Hawkgirl owes her powers to a belt of Nth metal, a substance native to the planet Thanagar (once home of another pair of Hawk-heroes, Katar Hol and Hawkwoman). The metal is psycho-reactive, responding to its bearer's thoughts and in its base form has a number of electromagnetic/gravitational properties. To the Hawks, it grants the power of flight, superhuman strength, super-acute vision, and an enhanced healing/regeneration ability.
Additionally, she displays advanced hand-to-hand combat skills. Like Hawkman, she retains the knowledge of several lifetimes worth of fighting. Her preferred weapons are a spear or mace, but she has also been depicted using swords, axes, warhammers, shields, and other melee weapons. She possesses shooting skills from her times as the gunfighter, Cinnamon.
In addition, the Nth metal knife which murdered Hawkgirl in her original incarnation as Chay-Ara had an unusual effect upon her soul and that of her lover Khufu (Hawkman). The pair are locked in a seemingly endless cycle of death and rebirth throughout the centuries. While not a superhuman power per se, this propensity for reincarnation has allowed Hawkgirl to cheat death and return to active duty in her current incarnation.
Recently, Kendra has discovered that she had enhanced healing and limited hover abilities when not wearing Nth metal. She speculates that this is due to her prolonged exposure to the substance. It remains to be seen if she still possesses these abilities now that she is Shiera Hall once again.