The first woman considered to be Queen-Regnant of England, though her reign is disputed, was Matilda, formerly Empress of Germany. Her mother was Matilda of Scotland.
Almost-Queens: Matilda of Scotland

The first woman considered to be Queen-Regnant of England, though her reign is disputed, was Matilda, formerly Empress of Germany. Her mother was Matilda of Scotland.
Sometimes, while reading history, one comes across a fact one never expected to see. Would anyone expect an ancient Indian Emperor to have a Greek wife? Well, he did.
Queen Musa of Parthia's origins are surprising for a great ancient queen, but perhaps those very origins are why we never hear of her.
Elena Glinskaya ruled what would become Russia as regent for her son, wisely and ably in fact, until her life and reign were brought to brutal ends.
Amalasuntha ruled Rome after the Roman Empire's fall. She is known for being a wise leader of the Ostrogoths, first as regent, then as the ruling monarch.
Alice Perrers was quite the ambitious mistress, though we have to have some sympathy for her—she has been hated in her time and ever since.
Anne Hyde nearly became Queen of England but died before her chance to. She was a commoner who, through good luck, became the mother of Queens Mary II and Anne.
Sarah Lyttleton was a beloved mother figure to Queen Victoria's nine children, all of whom kept fond memories of her as they lived their grand futures.
When Anne Boleyn was executed, her husband famously moved on eleven days later. But her mother’s devastation often goes unnoticed.
Blanche of Castile served as regent of France on two occasions and held great power in the country even when she wasn’t ruling.