UK
For basic biographical details, you would do well to get one or more of the following:
Who's Who
The famous red book contains 32,000 biographies of 'the great and the good'. CD and online versions provide access to over 100,000 biographies going back to the very first biographies from 1897. An essential research tool.
Debrett's People of Today
Contains 25,000 biographies of leading figures. "The ultimate list of who is in and who is out at the top of British Society" according to The Independent. As there is some variation between this and Who's Who, also essential for research. Available online (£100 per year) and on CD.
Debrett's also publish Peerage & Baronetage which contains the genealogical details of every British duke, marquess, viscount, earl, baron and baronet, together with all the living members of their families in the male line. Useful for researching toffs.
Burke's Peerage, Baronetage & Knightage
Like Debrett's, Burke's is synonymous with nobs and toffs. The latest edition of Burke's includes for the first time Scottish and Irish Chiefs and Scottish Feudal Barons. Also available online.
ThePeerage.com
In a similar vein to Peerage & Baronetage, provides a genealogical survey of the peerage of Britain as well as the royal families of Europe. FREE
Know UK
An online resource of over 100 biographies, directories, encyclopaedias and other reference works, including Debrett's, Who's Who and many other useful sources. An invaluable resource, especially as it is available free from some libraries (otherwise expect to pay £1000+ per year). FREE-ISH
Credo Reference (formerly Xrefer)
Similar to KnowUK with almost 250 different reference sources; Debrett's, Who's Who, etc. Also available free from some libraries. FREE-ISH
192.com
Styles itself as "the most comprehensive database of names and addresses" in the UK, with over 160 million records taken from Directory Enquiries and the Electoral Roll. Very useful for finding home addresses not listed in standard biographies. FREE-ISH
192.com also produce the UK Info CD or 'People Finder', described by PC Format as "the most powerful people finder known to man". Slight exaggeration perhaps, but it can prove very useful in finding prospects' home addresses and discovering who else lives in their area.
The UK Electoral Roll
Offers a variety of search options. For example, with one package you can carry out unlimited searches of the electoral roll by full name, forename, surname or address, a package which includes unlimited searches of the Birth, Death and Marriage records.
Or how about using their Property Ownership Search, which allows you to find the title for any UK Property (England, Ireland and Wales only). Details available include date of purchase, full names of the owners and price paid, if available.
Tracesmart
Also has a comprehensive database of electoral roll information going back to 2003 and also allows searches of Birth, Death and Marriage records. FREE-ISH
Who Owns Scotland
Not very many people, it would seem. Comprehensive online database of land ownership north of the border. FREE
UK Honours
Has lists of honours going back to 2003, useful for checking who has been awarded what honour for what reason. Also provides useful information about types of honours and the difference between honours and peerages.
International
International Who's Who
Published annually since 1935, now contains 20,000 biographies of the world's most prominent and influential personalities. Also available online.
International Who's Who of Women
A biennial guide to "the most influential and distinguished women throughout the world" - well, 6000 of them, anyway - which "reflects the growing role of women in modern society." Quite. One hopes that the actual entries are less patronising.
The same publisher also produces the International Who's Who of Authors and Writers, the International Who's Who of Classical Music and the International Who's Who of Popular Music.
Biography
From the creators of the Biography Channel; 25,000 biographies searchable by name and keyword. Mostly dead people, but may be of use. FREE
Biogs.com
Provides a range of biographies listed alphabetically and by subject. FREE
NNDB
Contains profiles of over 20,000 people, but "mostly exists to document the connections between people, many of which are not always obvious." FREE
Wikipedia
The free encyclopaedia contains biographies of a large number of people, although the level of detail varies greatly. Many of them are also listed by various sub-categories (nationality, occupation, people with disabilities, dyslexia, epilepsy, etc.) which could prove useful. FREE
Infobel
Comprehensive list of directory enquiries for the WHOLE WORLD! (cue dramatic music).
Actors, singers, artists, etc.
Spotlight
Founded in 1927, this series of directories now contain over 30,000 performers, including actors and actresses, child artists, presenters, stunt artists and dancers. Online search facility FREE
Red Pages
Celebrity contacts directory providing agent, publicist and management details for over 10,000 international celebrities, including actors, musicians, models, comedians, footballers, reality stars and industry leaders. Also available online, allowing one to search for celebrities by their charity affiliations, interests and endorsements.
Hello magazine
Has quite detailed profiles on its website of the various attention seeking actors, musicians and other talentless freaks celebrities who feature in the magazine. FREE
Specialist
Dod's Parliamentary Companion
Contains biographies of MPs, peers and other Parliamentary officials. Also available online.
Who's Who in Charities
Contains biographies and entries for 50,000 trustees and executives at the UK's leading charities. "Ideal for prospect research" says the blurb, although given that they've discontinued the CD version, it is now less than ideal.
Who's Who in the City
This comprehensive networking guide to the City of London contains 16,000 biographies of key City figures, 5000 company profiles and a useful 'who advises who' section.
Solicitors and Barristers
Profiles are provided by The Legal 500, UK and worldwide. FREE