Thomas Topp was born in Southampton, Hampshire, England in late 1884 and his birth was registered in the first quarter of 1885. 

He was the son of Charles Topp (1857-1940), a master butcher, and Ellen Spencer (1853-1902). His father was originally from Poole, Dorset and his mother from Basingstoke, Hampshire and they married in Southampton in 1878.

Thomas, known as Tom, had five known siblings: Charles Frederick  (b. 1878), Ellen Louisa (b. 1880), William George (b. 1881), Lydia (b. 1882) and Laura (b. 1890).

On the 1901 census Tom, his sister Laura and his parents were listed as living at 4 Cuckoo Lane, St Michael, Southampton. Curiously, and for reasons unknown, Tom is listed as a seven-year-old and his sister Laura as a three-year-old; and his parents have also shaved over a decade off their own ages. His mother passed away in 1902 aged 49. Tom would later follow in his father's footsteps and become a butcher.

Thomas was married in Southampton in the second half of 1910 to Alice Louisa Cull (b. 13 March 1889), a native of Eastleigh, Hampshire and daughter of railway labourer James Cull and the former Charlotte Littlefield.

Tom and Alice welcomed a son named Thomas Frederick on 25 September 1910.

On the 1911 census Thomas, his wife and son are living at 89 Milton Road, Southampton with his married sister Lydia Crow, who marine steward George Frederick Crow. His widowed father was listed as a lodger at 49 South Front, Southampton, the home of Titanic crew survivor Walter John Williams and his family.

When he signed-on to the Titanic on 6 April 1912 Topp gave his address as 89 Millbrook Road, Southampton. His previous ship had been the Olympic and as second butcher he received monthly wages of £5, 10s. Also serving aboard was his brother-in-law George Crow, a steward. 

Thomas Topp died in the sinking and his body, if recovered, was never identified; his brother-in-law George Crow was among the saved. The following death notice appeared in the Hampshire Advertiser on 27 April 1912:

TOPP--On the 15th inst., on the s.s. Titanic, Thomas Topp, of 89, Milton road, Fitzhugh, Southampton, aged 26.

Tom's widow Alice was remarried in Southampton in 1917 to James Badminton (b. 10 April 1862), a widowed railway wagon maker who was nearly thirty years her senior. James had sired five children from his previous relationship to Martha Hannah Wood who had died in 1913. He and his young bride Alice would have no children of their own; they settled in Eastleigh where Alice was made a widow once again in 1943. She passed away in Basingstoke, Hampshire in 1974 aged 85.

Thomas' son Thomas Frederick never married and later worked as an interior furnisher in railway coaches. He remained at the family home, 39 Newton Road in Eastleigh, Hampshire until his death on 23 August 1985 aged 74.