Name Origin
It is very unlikely that there is a single origin to the name, despite many people believing that "all Hollyers are related". There are some early 14th century references to a Robert le Holyere and Adam Holiere which might suggest a Norman origin. One source does make this assertion, based on the Norman Osmund Hoielor of 1108.
An early Warwickshire reference is from 1325 and mentions an Adam de Holyer being witness to a land deed at Canley in Stoneleigh. However, a far more significant reference from 1373 is to a John Holyer, bailiff of John de Clynton, knight, in his manor of Shustoke, Warwickshire. In 1433, there is a record of a Roger Holyer holding property in the nearby Parish of Arley. By the time parish registers started in 1539, there are frequent records of Hollyers at Shustoke and surrounding parishes in North Warwickshire.
However, the name had also by that time spread out to the neighbouring counties of Staffordshire, Leicestershire, Derbyshire, and Oxfordshire. But quite separately the name is also found spread thinly across the Southern counties from Kent to Hampshire, including the Isle of Wight.
Early Kent & Sussex records
In the manuscripts of the Corporation of New Romney, there is a reference from 1399 of a Robert Holier being paid to ride to Sandwich, London and along the coast 'to obtain news as to the arrival of the present King' [Henry IV]. There was also a Holyer family owning land at Hooe in East Sussex with early references in 1427 and 1440. Another record from 1444 suggests that the land was owned by 'John Holyer of Canterbury', reinforcing the idea of an early presence in Kent. This same Hooe family must be the one mentioned in the Manorial Court records of Moorhall, Ninfield in 1472. Joan, late wife of Richard Holyer failed to attend the court "to do fealty for a tenement once John Holyer's". In his will of 1493, Thomas Baker of Cranbrook, Kent, leaves £5 to Johanne Holyer. In 1569 there is a record of a marriage of Thomas Holier to Joan Myer at Goudhurst. Also in 1569, the Canterbury Cathedral Records show amongst their Communicants Lists a 'Mother' Holyer and John Holyer from Apuldore [Appledore]. While the main Parish Registers for Appledore only survive from 1700, there are some early register copies at the Society of Genealogists which show no less than 5 Holyer burials at Appledore in 1563. Appledore is close to Woodchurch, where the Holyer name 'takes off' after 1737. Back in East Sussex, the Borough Records at Rye mention a William Hallyard (or Hollyer) in 1598.
This presents a patchy and inconclusive set of records, but providing some evidence that the Holyer name has been present in Kent over many centuries before the main recorded expansion after 1737.