Fitzpatrick, William John (1830–95), historian, was born 31 August 1830 in Thomas St., Dublin, son of John Fitzpatrick, tallow chandler and merchant. He began his education at a local Church of Ireland school before attending Clongowes Wood College, Co. Kildare. His father left him a sizeable inheritance on his death, which allowed Fitzpatrick to devote himself to historical research and writing. He began writing while in his early twenties, and was to publish numerous books over the next forty years. The first, The life, times and contemporaries of Lord Cloncurry, appeared in 1855. In 1855 he began writing a series of letters to Notes and Queries questioning the authorship of the Waverley novels. He published a separate pamphlet on the subject in 1856, claiming that the novels had in fact been written by Sir Walter Scott's brother, Thomas Scott, who was a regimental paymaster in Canada. This claim was repudiated by Walter Scott's daughters in a letter to The Times in June 1857. A tireless researcher, Fitzpatrick trawled through documentary sources to satisfy his desire for accurate information. From the beginning of his writing career, he had been obsessed with the secret history that surrounded the 1798 rebellion and the passing of the act of union. This led him to publish Lord Edward Fitzgerald or notes on the Cornwallis papers (1859), The Sham Squire and the informers of 1798 (1866), and The secret service under Pitt (1892), one of his most important works. Many of his later biographical works were also of major importance and were well received, notably The life and times of Bishop Doyle (1861) and The correspondence of Daniel O' Connell (1888). Other publications, however, such as Irish wits and worthies (1873) and A life of Charles Lever (1879), seemed poorly researched and hastily written and were severely criticised.
Alongside his historical work he served as a JP for the counties of Dublin and Kildare and twice acted as high sheriff for Co. Longford. He also served for a short time as the Uruguayan consul in Dublin, and was invited to stand as a parliamentary candidate for Tipperary in 1869, but declined. Elected MRIA (January 1875), he was also elected honorary professor of history at the Royal Hibernian Academy of Arts (1877–80, 1882–95). Pope Leo XIII appointed him a knight of St Gregory the Great (1889) for his work on O'Connell, and he was awarded an honorary LLD from the RUI. He died 24 December 1895 at his Dublin home, 49 Fitzwilliam Square, and was buried in Glasnevin cemetery. His final book, A history of the Dublin catholic cemeteries, published posthumously (1900), was edited by his son Gerald P. Fitzpatrick. While some of Fitzpatrick's later works were poor in terms of style and content, his work on the secret history of Ireland at the turn of the eighteenth century was of considerable importance and established him as one of the most popular Irish writers of his era.
There are collections of Fitzpatrick's paper in TCD and the NLI. A portrait by Stephen Catterson Smith (qv) the younger is held in the NGI. Another portrait hangs in the Gilbert Library, Pearse St., Dublin.