Halleigh is a creative spelling of Hallie, from English surname roots meaning 'dweller at the hall meadow.'
Halleigh is a phonetic variant of Hailey and Hayley, names rooted in the Old English toponym hæg lēah, meaning "hay clearing" or "hay meadow" — the kind of rural English place name that passed into personal use through the medieval English tradition of taking surnames from one's village. The place Hailey exists in both Oxfordshire and Hertfordshire, and it was from surnames derived from such locations that the given name eventually emerged, following the Victorian fashion for bringing surnames to the front of a name.
The name achieved its most famous association through Edmund Halley (1656–1742), the English astronomer who calculated the periodicity of the comet that now bears his name — though Halley himself pronounced his name to rhyme with "valley." Popular culture nonetheless cemented the "hay-lee" pronunciation, and when the comet's 1986 return coincided with a surge in the name's popularity, the connection felt inevitable. The astronomer's association lends the name an unexpected scientific pedigree, a glancing connection to the stars.
Halleigh's specific spelling, with its doubled L and the -eigh ending borrowed from names like Leigh and Raleigh, is a distinctly late 20th-century American contribution — an effort to give the name visual uniqueness and a certain Tudor-esque flourish. It surged in popularity through the 1990s and 2000s and now carries the warm, sun-drenched associations of that era's naming culture.