John "Jack" McGargill (c. 1859–4 July 1937) was a coach for the Port Adelaide Football Club for 23 seasons between 1886–1908.

During his coaching career he guided Port Adelaide to four SAFA premierships and the 1890 Championship of Australia.

When I first met Jack he was massaging such men as Aleck and Ken McKenzie, Percy Gardiner.

Otto LeStage, "Tick" Phillips, George Earle and other famous magenta jersey wearers in 1895.

He had nothing like the present day facilities such as trestles, lockers, laundry or punching and pinching the muscles into dough, but he turned out just as good sound athletes or even better than they do to-day.