The name Hadley is an English given name with origins dating back to the Anglo-Saxon era. It is derived from the Old English words "hæþ" meaning "heather" and "leah" meaning "clearing" or "meadow." Together, these words form the meaning "heather clearing" or "heather meadow," suggesting a connection to the English countryside and natural landscapes.

While the exact origin of the name is unclear, it is believed to be a locational surname that later transitioned into a given name. Historically, locational surnames were often derived from the names of towns, villages, or geographic features where people lived or came from. In this case, Hadley likely referred to various places in England bearing the same name, such as Hadley in Shropshire or Hadley in Worcestershire.

One of the earliest recorded instances of the name Hadley can be found in the Domesday Book of 1086, a comprehensive survey of land ownership and taxation in England commissioned by William the Conqueror. However, it is unclear whether this refers to a person or a place.

Throughout history, the name Hadley has been borne by several notable individuals. One of the earliest examples is John Hadley (1682-1744), an English mathematician and inventor who created the Hadley's quadrant, an important navigational instrument used in maritime navigation.

Another prominent figure was Stephen Hadley (1750-1822), an American lawyer and politician who served as the 6th Lieutenant Governor of New York from 1804 to 1810. Additionally, John Hadley (1731-1764) was an English composer and organist known for his compositions for the Anglican Church.

In the literary world, Anne Hadley (1630-1685) was an English Quaker writer and preacher who published several religious works during the 17th century. Furthermore, John Hadley (1907-1987) was an American historian and author who specialized in the American Revolutionary War and the early years of the United States.

While the name Hadley has been more commonly used as a surname throughout history, its use as a given name, particularly for males, has endured over the centuries. The name's connection to the English countryside and its longstanding presence in historical records have contributed to its enduring popularity.