These are databases or dictionaries organized around individual people, covering Britain and Ireland in the long eighteenth century, and in most cases beyond this time span.
Africans in Ireland: Spanning 1578 to 1921, this database “brings together information on African-descended people who lived in, travelled through, and engaged with Ireland …. Drawing on a wide range of archival and historical sources, the database brings together evidence that is often dispersed across newspapers, census records, correspondence, memoirs, government documents, and other collections.”
BBTI: British Book Trade Index, covering people working in this sector up to 1851. Originally created by the Bodleian, but taken down, now resurrected by the Grub Street Project.
BIFMO: British and Irish furniture makers from the beginning of the 16th century to the onset of the Great War (1914).
Booksellers and Printers who Were at Work in England, Scotland and Ireland from 1641 to 1667: Plomer’s 1907 book, hosted by Wikisource.
British artists’ suppliers: Courtesy of the National Portrait Gallery, covering the arts supply trades, 1650 to 1950.
British picture framemakers: Courtesy of the National Portrait Gallery, covering picture frame makers, 1600 to 1950.
British picture restorers: Again via the N.P.G., covering 1600 to 1950.
CCEd: Clergy of the Church of England, 1540 to 1835.
Digital Panopticon: Tracing London Convicts in Britain & Australia, 1780 to 1925.
Early Black Presence in Bristol: 792 entires, covering Black people on Bristol up to 1860.
Early Modern Practitioners: Many lists of early modern medics.
FreeReg: Free and open transcriptions of parish registers and related material, 1538 to 1837.
History of Parliament Online: Biographies of MPs from 1386 to 1832.
Legacies of British Slavery: Excellent resource, detailing the British slave-owners paid ‘compensation’ for the emancipation of the enslaved after 1833.
Munk’s Roll: of the fellows of the Royal College of Physicians. Vol. 2. covers the eighteenth century.
Runaways: Nearly 900 runaways from slavery in Britain, through the advertisements taken out by slaveowners, 1700 to 1780.
Scottish Architects: A dictionary spannng 1660 to 1980. Includes Buildings and Practices, but oddly doesn’t appear to allow browsing of the entries, only searching.
Scottish Book Trade Index: people involved in printing in Scotland up to 1850. Separate from the British Book Trade Index above.
Sculptors in Britain, 1660-1851: Via the Henry Moore Foundation.
Smuggling Prosecutions: People prosecuted for smuggling, 1722 to 1732.
Switching the Lens: Records of circa 2,600 black, African and Asian lives in London, 1561 to 1840.
Additionally, there are a number of biographical dictionaries published in the nineteenth or early twentieth century, now out of copyright and so freely available. So far, I have found just the one that covers the eighteenth century and is not duplicated by a modern database, which is Plomer’s dictionary of printers and booksellers. There is also the monumental 16 volume dictionary of London theatre staff by Highfill, Burnim and Langhans, an astonishing resource that happily has been made available under a creative commons license.
Highfill, Burnim, Langhans, A biographical dictionary of actors, actresses, musicians, dancers, managers & other stage personnel in London, 1660-1800. Hathi Trust.
Plomer, A dictionary of printers and booksellers in England, Scotland and Ireland, and of foreign printers of English books 1557-1640. Archive.org
Plomer, A dictionary of the printers and booksellers who were at work in England, Scotland and Ireland from 1668 to 1725. Archive.org.
There are also openly accessible digital Dictionaries of National Biography for Ireland and Wales; and many people of British and Irish birth will be found in those for Australia and Canada. A Scottish DNB of 68 volumes, originally published between 1885 and 1904, has been fully digitized and is listed on Electric Scotland.
Finally, Wikipedia has many extensive and multiplying categories for Eighteenth Century English People and Eighteenth century English People by Occupation.