Gosse married Gertrude Ritchie in 1860, who died of
typhoid fever five months later. Gosse married Agnes "Aggie" Hay (1853–1933), a daughter of
Alexander Hay and his first wife Agnes née Kelly (1818–1870) on 22 December 1874. (Hay's second wife, Agnes Grant née Gosse, was William's sister.) William and Aggie had three children: • William Hay Gosse MC (1875–1918) was killed in action in France. He married Muriel, née Davidson, who died in 1920. Their son
George Gosse (1912–1964) was awarded the
George Cross in 1946; • Sir
James Hay Gosse (1876–1952) married Joanna Lang, daughter of
Tom Elder Barr Smith – they had a daughter and four sons; and • Edith Agnes Gosse (1878-). Harry Gosse ( 1888), the eldest son of Dr. William Gosse, died around 1 June 1888, four miles north of Delamere Station, where he had been working. A brother-in-law, and also nephew,
William Gosse Hay (1875–1945) was an author. A sister-in-law, and also niece, Helen (1877–1909), and her mother (William's sister), were lost at sea on the ill-fated . Other descendants include former Australian Minister for Foreign Affairs and Liberal Party leader
Alexander Downer. ==See also==