10 Most Powerful Characters Killed By Captain America
9. Jack Flag - Captain America: Steve Rogers #1
Easily the most shocking controversial entries on this list, Steve Rogers' out-of-left field turn to HYDRA did not sit right with many Marvel readers, and the response was vitriolic enough to be softly retconned not long after its debut.
Following various crossovers where the hero became the head of S.H.I.E.L.D. and lost his abilities, a now-rejuvenated Rogers resumed his field duties but the (convoluted) process that restored his strength led to his turn towards the Nazi group. It was later revealed that this version of Cap was not the real deal as the legitimate Steve was locked away in the Cosmic Cube.
Despite eventually being stopped, the damage that HYDRA Cap did was immense. In addition to his grand crimes, this villainous incarnation threw part-time Guardians of the Galaxy member Jack Flag to his demise after the latter disobeyed his orders.