Thomas John Barnardo (4 July 1845 — 19 September 1905) was an Irish/British philanthropist and founder and director of homes for destitute children, born in Dublin. From the foundation of the first Barnardo's home in 1870 to the date of Barnardo’s death, nearly 60,000 children had been rescued, trained and placed out in life. The work of Thomas Barnardo is continued today by the British charity Barnardo's.

His medical work in the East End of London during the epidemic of cholera in 1866 first drew his attention to the great numbers of homeless and destitute children in the cities of England. Encouraged by the support of the seventh Earl of Shaftsbury and the first Earl Cairns, he gave up his early ambition of foreign missionary labour, and began what was to prove his life’s work. The first of the "Dr Barnardo’s Homes" was opened in 1870 at 18 Stepney Causeway, London. From that time the work steadily increased until, at the time of his death, in 1905, there were established 112 district "Homes," besides mission branches, throughout the United Kingdom.