This post is a bit long, a bit fact-heavy, and there are plenty combative ladies I didn’t have room to include. This is one of my favorite topics along with military history, so feel free to mention anyone I didn’t get to today!
Lakshmi Bai

An artist’s depiction of Rani Lakshmibai of Jhansi in battle with the British, with her stepson, Damodar.
Lakshmi was her stepson’s regent over Jhansi, a small principality in northern India, until 1857, when a mutiny led to the slaughter of British soldiers and civilians. The British saw it fit to blame Lakshmi and when it became clear that she wouldn’t be allowed to retain control of her kingdom, Lakshmi led a rebellion, even riding with her army against the British. She was shot with a musket, but returned fire before being finished with a saber.
Nzingha
A seventeenth century queen of the Ndongo and Matamba Kingdoms of the Mbundu people in modern day Angola, Nzingha rose to power around 40 shortly after the death of her brother, Mbandi, and spent the rest of her life fighting against the Dutch and Portuguese. She led many battles and campaigns against the European invaders up until her death in 1663 at eighty years of age.
Boudicca
When King Pragustus died in 60 A.D., the Romans brutalized his wife Boudicca and their daughters and attempted to seize the king’s estate. At this, other tribes flocked to Boudicca’s aid in an uprising against the Romans. Led by Boudicca, the Celtic armies sacked Camulodunum (modern Colchester), Londinium (modern London), and Verulamium (modern St. Albans) before being defeated by Suetonius Paulinus.
Cynane
There is a lot of ambiguity surrounding Cynane, but we know this much—she was Alexander the Great’s half sister by Philip II’s Illyrian wife, she was trained by her mother in the martial arts, and she was not afraid of taking what she wanted. There are even some stories that place her on the battlefield with Alexander doing single combat with enemy leaders. Alexander tried marrying her off to get her out of the way, but after his death she turned up and demanded her daughter Eurydice be made empress to his heir. She was killed for her efforts, but in the end, Eurydice did become queen.
Artemisia I

Eva Green as Artemisia in 300: Rise of an Empire. (Don’t get me started on this film’s historical inaccuracy. Just don’t.)
If you’ve seen 300, you probably know who this is, at least the fictionalized, sexualized version. Though sometimes confused with Artemisia II, Artemisia I rose to power as regent of Caria for her son after the death of her husband. Mentioned by Herodotus, Pausaniaus, Polyaenus, in the Suda, and Plutarch, all sources agree that Artemisia I was a cunning tactician and invaluable asset to Xerxes I. Famed especially for her feats in the Greco-Persian war, she distinguished herself at the naval battle of Artemisium, but disappears from the historical record after escorting Xerxes’ illegitimate sons to Ephesos after the Persian defeat at Salamis.