Athelstan, or Aethelstan, (895-940), a king of England, 925-40. On the death of his father, Edward the Elder (son of Alfred the Great), he became king of the West Saxons and Mercians but soon extended his rule over most of England. Athelstan was also acknowledged as overlord of Wales and most of Scotland. He was the first ruler to take the title of "King of All Britain." He was a popular ruler.