Soldier Boy is the reason The Boys were established in the first place, dating back to WWII, even though Homelander is the team’s main antagonist.
Although Homelander might be the first film that comes to mind when discussing The Boys’ superhuman antagonists, Soldier Boy’s hidden backstory shows that there wouldn’t have been a super-killing squad for Billy Butcher to lead in the first place if it weren’t for the franchise’s Captain America parody. This is because Gregory Mallory founded the group, recruited Butcher, and embarked on a mission to prevent Vought-America’s Supes from going out of control because of the original Soldier Boy.
Greg Mallory, who is already retired at the start of the series, was the head of the Boys before the Lamplighter killed his grandchildren, which caused him to give up on his goal and dissolve the group. Mallory was the one who leveraged his CIA connections to gain the team a mission statement and funds, as well as access to a supply of Compound V to equip the Boys to take on Supes head-on. A while later, Mallory returns to The Boys, telling Hughie Campbell about the true nature of Butcher and enlightening him about the group’s hidden past, which starts with Soldier Boy.
Mallory gives Hughie a rundown of his personal history in The Boys #53, written by Garth Ennis, John McCrea, and Keith Burns. He starts with his time in World War II. There, Mallory finds out that the superhero team “Soldier Boy and the Avenging Squad” has been formally assigned to his unit for political reasons. Disappointed with their strength and lack of self-control, Mallory nearly perishes when Soldier Boy’s clandestine reconnaissance exposes their location, resulting in the death of both Mallory’s soldiers and the original Soldier Boy’s squad. Despite suffering severe injuries, Soldier Boy manages to survive the carnage. However, Mallory is so furious over the fallout from his deeds that he uses a grenade to assassinate the so-called hero.
Once Mallory returns to America, he remains outraged by Vought’s use of Supes in war and the normal men they got killed. Joining up with the CIA, Mallory gradually makes the contacts to form the Boys, committing himself to making sure that superhumans never again become a part of warfare. This is due both to the disastrous consequences in WWII and a desire to see Vought fail in the mission that meant so many of his men never returned home. Throughout the long years of forming the Boys, it’s Soldier Boy who keeps Mallory motivated. In a pastiche of Captain America’s time in the ice, Vought keeps creating new versions of Soldier Boy, claiming they’re the never-aging original. Mallory watches this process from afar, understanding that while they may not say it, Vought’s long-term plan is to turn Supes into lucrative weapons of war, with Soldier Boy’s constant presence signifying this dastardly long game.
While Homelander is the Supe who finally led a short-lived superhuman revolt, and Black Noir is the sickening killer who brought him down, Soldier Boy is the only reason there’s a specific, dedicated force acting against them both. Without Soldier Boy’s disastrous WWII service, Mallory would have never created the Boys, recruited and trained Butcher, or left Hughie the resources to prevent his mentor’s massacre of anyone with Compound V in their system.