Sir Albert Hastings Markham, KCB (1841–1918), explorer, author, and officer in the Royal Navy, lived at 4 Onslow Square as a child.
Vice-Admiral Robert FitzRoy (1805–1865), commander of HMS Beagle, on board which the naturalist Charles Darwin (1809–1882) also sailed, lived at 38 Onslow Square.
[7] Fitzroy lived at No 38 from 1854 to 1865, when he committed suicide (but in another residence in Norwood), through guilt for his part in casting doubt about the truth of the Bible.
The sculptor Baron Carlo Marochetti – who cast the lions for the column – lived at number 34, and had a workshop and foundry nearby in Sydney Mews.
John William Crombie (1858–1908), a Scottish woollen manufacturer, folklorist and Liberal Party politician, died in the square.
[8] British billionaire Richard Caring lives in a "£40m mansion" with a two-storey basement, Park House, which replaced a 19th-century cottage that had been owned by Gert-Rudolf Flick, heir to German industrial wealth.