Who was the first Queen of England?
There is in reality probably. 5 different answers.
Let's go back, all the way back to the beginning.
So, England was first unified in 927 by King Æthelstan. Æthelstan never married, there is various theories on why he didn’t, some say he may have taken a vow of chastity, he may have wanted to delay his marriage to keep the English noble families vying for favour with the King to persuade him to marry into their family, the most likely reason, however, is that marriage would likely produce an heir, and he already had 2 heirs, in his younger brothers Edmund and Eadred. Having a son may have caused a succession crisis, and the last thing this new Kingdom needed was division.
Edmund succeeded his older brother in 939, his wife Ælfgifu of Shaftesbury, was his consort, some sources do call her Queen, while others call her a concubine, it’s important to note that until 1066, being the King’s wife doesn’t necessarily mean you are the Queen, for example, Alfred the Great’s wife was not a Queen.
The first ‘Queen’ that was actually anointed as Queen was Ælfthryth, wife of King Edgar, she was anointed Queen at Edgar’s second coronation at Bath in 973.
The issue at times would be that a King may have a wife who wasn’t a Queen and then remarry a lady that was either a Queen or more legitimate than the first wife. The question then is, who is the king's heir? The eldest son of the King or the more legitimate son of the King and Queen. This led to a succession crisis in both 924 and 975, luckily both situations didn’t lead to large scale conflicts.
Moving on to the post-Norman invasion period, and we see 3 figures claim or potentially have power in their own right.
Starting with Matilda, Lady of England. She was the daughter of King Henry I, who died without having any legitimate sons that had survived him, so he announced Matilda as his heir, which was commonly accepted, however upon his death, the country was split between Matilda and her cousin, Stephen. During this time Matilda only ever took the title Lady of England. Stephen eventually came out on top, however, it was agreed that Matilda’s son Henry, would be Stephen’s heir, who went on to be Henry II, one of England’s most successful Kings.
Then to the Tudor period. Around the death of Edward VI (son of Henry VIII), Edward and his government attempted to deny the throne to his sister Mary, due to her being a Catholic (during the Protestant Reformation). Instead the throne went to Edward’s cousin, Lady Jane Grey, who was Queen of England …………. for 9 days.
Mary had gathered support in East Anglia, which was a more Catholic area of the country, soon after, support for Queen Jane severely died down, leaving the throne open for Mary to take back, she imprisoned Jane and her father in law, John Dudley, Earl of Northumberland, who was Edwards’s regent and the main driving force behind Jane’s accession. Hence forth Mary became Queen in her own right, and was the first Queen to rule England. She did however marry King Phillip II of Spain, but she still ruled in her own right, although there would be some uncertainty surrounding the future, would their child rule England?, Spain? or both.
Mary died 5 years later, without having any children, the throne was then passed on to her younger sister Elizabeth I, who went on to be a very successful Queen and enjoyed a long reign.
In Summary
The first to be anointed ‘Queen of England’ or ‘Queen of the English’ was Queen Ælfthryth, wife of King Edgar, she was what we would call ‘Queen Consort’
The first the Rule in their own right as Queen of England, was Queen Mary I. She was what we would call ‘Queen Regnant’