Mr Denis Lennon was born on 9 December 1891 in Currycreaghan, Ballymahon, Co Longford, Ireland.
He was the son of William Lennon (b. 1846), a farmer, and Bridget Mullin (b. circa 1853), Longford natives who had married on 25 April 1887.
One of six surviving children from a total of seven, Denis' siblings were: Eliza1 (b. 4 April 1888), Bridget (b. 21 August 1890), William (b. 22 July 1889), John (b. 27 October 1893), Anne Maria2 (b. 8 April 1897) and Kate (b. 30 September 1898). His sister Bridget was born disabled and lived only one day.
On both the 1901 and 1911 census records Denis' family were living in house 12 in Currycreaghan; he would be absent from the 1911 census with his family however and was listed elsewhere as a shop assistant and living with Delia Mullin and her family of house 3, Clarinbridge, Co Galway. Delia's youngest child was an 18-year-old daughter named Mary.
Denis and Mary, the latter not long out of convent school, fell in love and made plans to steal away to America. Originally booked to travel aboard Cymric, the coal strike changed their plans and they boarded the Titanic at Queenstown as third class passengers (ticket number 370371 which cost £15, 10s) and were using the names Denis and Mary Lennon.
Mary's brother Joe (and possibly also her mother) reportedly pursued the couple all the way to Queenstown, Joe carrying a loaded firearm in his fury, but they reached the dock too late. It has been suggested that Mary Mullin and Denis Lennon were cousins, the latter's mother's maiden name also being Mullin, but this was not the case.
Denis Lennon, along with Mary Mullin, died in the sinking. Their bodies, if recovered, were never identified.
Denis' family remained in Currycreaghan; his father William died 20 June 1929 from senility and his mother two years later on 19 May 1931 from influenza.