Athletics, men's Marathon...well, this is not so easy...but despite names like Zatopek, Kipchoge and the Italians, I think the best of them all is still Abebe Bikila, who's therefore my pick.
Athletics, women's Marathon...the strongest marathon runner ever beyond any reasonable suspect, Naoko Takahashi.
Rowing, men's Quadruple Sculls... Italy (2000), by far the strongest boat ever to compete in this discipline.
Rowing, women's Quadruple Sculls... China (2020)...Germany here pay the prize of the GDR age in my consideration.
Taekwondo, men's heavyweights... Carlo Molfetta...pretty partisan vote, but no other champion in this class is tickling my mind enough to earn my pick.