Sydney Smith Haldimand Dickens (18 April 1847 – 2 May 1872) was a Royal Navy officer; the fifth son and seventh child of English novelist Charles Dickens and his wife Catherine.
An endearing child, nicknamed "The Ocean Spectre" and "The Admiral" by his father, Sydney Dickens was born at 3 Chester Place and baptized at the church of St. Mary in Marylebone in London on 24 June 1847, his godfathers being William Haldimand of Lausanne, and Henry Porter Smith (1797 - 1880), an actuary for the Eagle Life Assurance Company. He was educated at Brackenbury's Military School at Wimbledon and at Mr Gibson's boarding school in Boulogne-sur-Mer, with his brothers, Alfred and Henry.
When aged 3, and staying with the family at Broadstairs, his father asked him if he would walk to the railway station to meet John Forster, who was coming for a visit. Without hesitation Sydney answered "Yes" and set off through the garden gate and down the street until another of the children ran after him and fetched him back. Aged 13 he joined Eastman's Naval Academy in Southsea, intending to train as a naval officer, a move designed by his father to encourage him to become self-sufficient in life. As a boy he had shown great energy and character, and was described by his father as a "born little sailor". On 11 September 1860, aged 14, Sydney Dickens joined the Royal Navy as a cadet on the training ship HMS Britannia. After his initial training he was posted to HMS Orlando on 6 December 1861.