'An illustrated collection of 50,000 specially written biographies of the men and women who shaped all aspects of Britain's past, from the fourth century BC to the year 2000.' (From ODNB). We also have volumes 1-60 in print.
See also the older edition of Dictionary of National Biography, edited by Leslie Stephen (London, 1885-1901), also available online.
'The landmark American National Biography offers portraits of more than 17,400 men and women -- from all eras and walks of life -- whose lives have shaped the nation' (from About the ANB). We also have volumnes 1-24 in print.
'A collaborative project between Cambridge University Press and the Royal Irish Academy, is the most comprehensive and authoritative biographical dictionary yet published for Ireland. It contains 9,014 signed biographical articles which describe and assess the careers of subjects in all fields of endeavour, including politics, law, religion, literature, journalism, architecture, painting, music, the stage, science, medicine, engineering, entertainment and sport.' (from database homepage)
The Dictionary of Welsh Biography down to 1940 (London, 1959) Olin Stacks DA710 A1 B913