William Ferguson (c. 1809 – 3 December 1892) was a pioneer settler of South Australia, one of the last surviving emigrants on HMS Buffalo in 1836.
Ferguson was a farmer born in Hawick, Scotland, and emigrated in 1836 on what has been termed the "First Fleet of South Australia" on Governor Hindmarsh's flagship Buffalo.
Ferguson was present at the Proclamation ceremony by the Old Gum Tree on 28 December 1836, and helped thatch the roof of the original Government House.
He also purchased a 248 acres (100 ha) part of section 251, Hundred of Adelaide, which he named "Roseville", again for his wife, and they lived there for around ten years.
Apart from his farming and land speculation activities, Ferguson was a partner with Robert Cock, for whom Cox Creek was (mis)named, as auctioneers.