Who was the last Queen of England  

Queen Elizabeth I was the last Queen of England. Since her death in 1603 there has only been a Monarch (king or queen) of the United Kingdom.  Her successor was James Stuart of Scotland who became James I of the United Kingdom. James’s accession meant that the three separate kingdoms of England, Scotland and Ireland were now united, for the first time, under a single monarch.
Queen Elizabeth I was  not only the last Queen Regnant* of just England, but also the last Monarch of just England.