Heylyn or Heilyn is a name of Brythonic origin meaning cup-bearer. Characters bearing the name occur in stories found in the Red Book of Hergest

Red Book of Hergest

The Red Book of Hergest is a large vellum manuscript written shortly after 1382, which ranks as one of the most important medieval manuscripts written in the Welsh language. It preserves a collection of Welsh prose and poetry, notably the tales of the Mabinogion, Gogynfeirdd poetry...

 and other collections of Welsh history and legend.

The Heylyn family came from Pentreheylin in the parish of Llandysilio

Llandysilio

Llandysilio is a village and community in the Welsh county of Powys.Its population at the 2001 Census was 962. The present parish church, dedicated to Saint Tysilio, dates from 1867 but tradition states that a church was founded here by Tysilio in the seventh century.- External links :*...

 Montgomeryshire. The family were hereditary cupbearers to the Princes of Powys, and a pedigree dates back to around 1000 AD. Grono ap Heylyn was commissioned by Llewelyn the Last in peace negotiations with Edward I of England

Edward I of England

Edward I , also known as Edward Longshanks and the Hammer of the Scots, was King of England from 1272 to 1307. The first son of Henry III, Edward was involved early in the political intrigues of his father's reign, which included an outright rebellion by the English barons...

.

Heylyn or Heylin as a surname may refer to:

• Edward Heylyn
  Edward Heylyn
  Edward Heylyn was a merchant and entrepreneur who was one of the founders of the Bow porcelain factory.The Heylyn family originally came from North Wales. Heylyn was the third son of John Heylyn, a saddler of London who is said to have made a fortune supplying saddles for the Duke of Marlborough’s...
  
   (1695–1765), English merchant and entrepreneur, one of the founders of the Bow porcelain factory
• John Heylyn
  John Heylyn
  John Heylyn was an Anglican divine, who had a major influence on religious thought in eighteenth century England. Because of his interest in mysticism he was known as the Mystic Doctor....
  
   (1685–1759), Anglican divine, known as the Mystic Doctor
• Peter Heylin
  Peter Heylin
  Peter Heylin or Heylyn was an English ecclesiastic and author of many polemical, historical, political and theological tracts. He incorporated his political concepts into his geographical books Microcosmus in 1621 and Cosmographie .-Life:He was born in Burford, Oxfordshire, the son of Henry Heylyn...
  
   (1599–1662), English ecclesiastic and author of polemical, historical, political and theological tracts
• Rowland Heylyn
  Rowland Heylyn
  Rowland Heylyn was a successful London merchant, sheriff of London in 1624-5 and publisher of a Welsh bible in 1630.-Life:...
  
  (1563-1631) London merchant and publisher of a Welsh bible