Mr Thomas O'Brien was born in Bunavie, Grean, Pallasgreen, Co Limerick, Ireland around 1885.
He was the son of Patrick O'Brien (b. circa 1835), a farmer, and Margaret Tobin (b. 1854) who had married in 1873 in their native Co Limerick.
He was brother to eight known siblings: Mary (b. 1873), Patrick (b. 1875), Winifred (b. 1877), Bridget (b. 1879), Patrick (b. 1880), Margaret (b. 1883), Annie (b. 1888) and Barney (b. 1891).
Thomas appears on the 1901 census living at house 4 in Bunavie, Grean. His father had passed away by this stage, on Christmas Day 1893, and he was described as a farmer's son, his mother and his brother Pat now operating the farm.
Thomas later became involved with another Limerick native, Hannah Godfrey (b. 1884), a native of Cappamore. It is not clear if the two were ever officially married but by early 1912 it was clear that Hannah had fallen pregnant and it was decided that the couple should emigrate.
Thomas and Hannah boarded the Titanic at Queenstown as third class passengers (ticket number 370365 which cost £15, 10s) and he was described as an agricultural labourer. They were travelling to Chicago, Illinois where Thomas' sister Mary Hunt lived at 638 Sherman Plaza. It is believed that he had several other siblings living in the Chicago locale.
Thomas died in the sinking and his body, if recovered, was never identified.
His widow Hannah later gave birth to their daughter on 3 September 1912 and named her Marion Columba O'Brien.
In the wake of Thomas' death came a wrangling over compensation between his widow and his family back in Ireland. Hannah was soon able to produce evidence that she and Thomas were married and she went on to benefit from various relief funds. In a terse letter to her sister-in-law Mary Hunt, Hannah said:
"You needn't worry about me. My baby and myself will be alright. I knew ye were all trying to get some money. I produced my marriage certificate, and I had the nearest claim. So you nor the lawyer needn't bother..."
Hannah was remarried and had a son before her untimely death in 1918.
His daughter Marion, a Titanic survivor in her own right, later married an Irishman, William J. Hanlon (1905-1975) and had one son and two daughters. She lived in Albany up until widowhood when she transferred to Tennessee where her daughter Catherine lived. She died in Manchester, Tennessee on 4 July 1994 aged 81 and is buried in St Agnes' Cemetery, Menands, Albany.