John Grey Weightman (29 March 1809 - 9 December 1872) was an architect based in Liverpool and Sheffield.
He was born on 29 March 1908 in Bawtry, South Yorkshire, the son of Robert Weightman and Mary Gray.
He trained in the offices of Charles Barry and Charles Robert Cockerell. Initially he practised alone in Sheffield from around 1832, but by 1834 he was working with Matthew Ellison Hadfield before entering a formal partnership in 1838 which lasted until 1858, after which he practised alone. He was corporation surveyor to the City of Liverpool from 1848 to 1865.
He married Mary Elizabeth Collinson (1802-1884). He died in Collingham, Nottinghamshire on 9 December 1872.