U.S. Agent

John Walker took the Power Broker's enhancement treatments, built a media career as the Super-Patriot, and then got handed the actual job when Steve Rogers walked away from the shield. The government could not have chosen a more instructive replacement. Walker had the strength, the training and the flag. What he did not have was Steve's restraint, and Mark Gruenwald's run methodically demonstrated the difference by having Walker kill people, snap under pressure, and watch his own parents murdered by extremists he provoked.

The character has been Marvel's stress test for American symbolism ever since. Rebranded as U.S. Agent, Walker has served on the West Coast Avengers, Force Works, Omega Flight and the Thunderbolts, usually as the guy the government trusts precisely because he will follow an order Steve Rogers would refuse. Wyatt Russell's screen version in The Falcon and the Winter Soldier hit the same nerve, and the audience reaction was exactly as uncomfortable as intended.

Mark Gruenwald and Paul Neary introduced Walker as the Super-Patriot in Captain America #323, a jingoistic media creation designed to make Steve Rogers look outdated. When the Commission on Superhuman Activities forced Rogers out, Walker became Captain America in issue #333, and the next two years are the most sustained deconstruction of the shield Marvel has ever published.

It ended badly. Walker's parents were murdered in front of a crowd, he killed in retaliation, and by Captain America #354 he had been rebranded U.S.Agent with a black costume and handed to the government as their own compliant Captain America substitute.

Since then he has cycled through the West Coast Avengers, Force Works, Omega Flight and multiple Thunderbolts rosters, occasionally as leader. Marvel keeps returning to him whenever a story needs someone who will do the necessary thing and feel entitled about it.