Sir John Badlesmere was a notable English knight and landowner during the 14th century. He is best known for his role in the political conflicts of the time, particularly during the reign of King Edward II. Badlesmere held the position of governor of Leeds Castle in Kent, which was a significant stronghold. In 1321, he became involved in the Despenser War, a conflict between supporters of the king and those opposed to the Despenser family. Badlesmere's actions during this period led to his eventual capture and execution in 1322, marking a dramatic end to his political career.