Sir John Audley Frederick Aspinall (25 August 1851 – 19 January 1937) was an English mechanical engineer who served as Locomotive Superintendent of the Great Southern and Western Railway (GS&WR) of Ireland and Lancashire and Yorkshire Railway (L&YR) of England. He introduced vacuum brakes to his locomotives in Ireland, a trend which was followed in Britain, and designed several locomotives. He was also president of the Institution of Mechanical Engineers and of the Institution of Civil Engineers.