William Beilby was an English glassworker known to have produced eminent enamelled glass during the later half of the 18th century.
Beilby's father William senior was a goldsmith and jeweller in Durham. Beilby, along with his brothers Richard, Ralph and Thomas were sent to grammar school during their childhood. Richard and Beilby, the oldest two, later went as apprentices to Birmingham, the former learning seal engraving and the latter enamelling and drawing. Soon the business of William senior failed, and in 1757 the whole family moved to Newcastle upon Tyne to start again. William senior died eight years later. Richard also died afterwards. Beilby and his sister Mary worked as enamellers for local glass makers.
As Ralph emerged as the business head of the family, Mary spent much of her time with Beilby, who had fallen in love with medieval Newcastle. Beilby was at once fascinated by the thriving glass industry about him, and it seems that it was at the Closegate in 1761 that Beilby became the first man in England to fire enamels into glass, so that they became virtually part of the glass itself.