In 1977, Doug Moench and Herb Trimpe launched Godzilla, King of the Monsters for Marvel Comics. The series itself often pit the beloved kaiju against some of the strongest heroes in the Marvel Universe. However, Godzilla's opponents really peaked in terms of strength towards the start of the run, when the kaiju faced off against, and defeated, a demigod, an Avengers and an Omega-level mutant -- all at the same time.
Godzilla, King of the Monsters #3 opens with the titular kaiju about to wreak havoc on San Francisco's Golden Gate Bridge. The police succeed in delaying the monster long enough for the Champions (Iceman, Angel, Hercules and Black Widow) and Dum Dum Dugan's Godzilla Squad to arrive on the scene. While Dugan attempts to dissuade the Champions from taking on Godzilla, they do anyway, and what ensues is disastrous.
Towards the start of the battle, Godzilla hits Angel with his tail, taking the mutant out for a short time. Hercules then manages to throw the monster onto its back, but Godzilla gets up almost immediately and breathes fire at his enemies. Their initial attempt at stopping Godzilla having failed, the team takes a moment to regroup. However, they're interrupted when the King of Monsters emerges from the water and smashes the Golden Gate Bridge, meaning both the Champions and Godzilla Squad failed their mission, although they did seemingly get all of the civilians on it to safety.
Iceman responds to the bridge's destruction by freezing Godzilla's head, but the monster breaks free. The Godzilla Squad then intervenes and drops a bunch of electrified nets on the King of Monsters. However, the attack doesn't really amount to anything. Finally, Hercules makes matters even worse when he throws a piece of the bridge at the monster. His mighty throw misses, and the debris hits a s helicarrier, which goes down into the San Francisco Bay. With his enemies defeated and the bridge destroyed, Godzilla walks off into the sea.
All of the opponents Godzilla takes down are powerful in their own right, especially when working together. However, Iceman, Hercules and Black Widow are three of the most notable heroes in the Marvel Universe and are not people to be taken lightly. Iceman, for example, is an Omega-level mutant, which means he's one of the Marvel Universe's biggest threats. Technically, Godzilla #3 actually predates the Omega-level designation, which was first used in Chris Claremont and John Romita Jr.'s Uncanny X-Men #208 in 1986. However, the designation of Iceman as an Omega-level mutant is more an acknowledgement of how deadly his abilities have the potential to be, so he was still an Omega-level mutant when he took on Godzilla, even if the term didn't yet exist.
As for the other two, Hercules has repeatedly proven himself one of the strongest characters in the Marvel Universe since his introduction in 1965's Journey into Mystery Annual #1. The hero essentially has unlimited strength. However, those abilities just didn't avail him against Godzilla, who finishes the battle without a scratch. Finally, Black Widow isn't known for having superpowers as formidable as her Avengers allies, but the former villain has repeatedly proven herself more than capable of standing up against some of the biggest threats in the universe. She hardly appears in the battle against Godzilla, in part because there's really not a lot she can do.
Although Godzilla doesn't kill any of his opponents, he absolutely humiliated the Champions when he went up against them. Not only did the team fail to protect the Golden Gate Bridge, but it also didn't even go after the kaiju to stop him once the battle was over. The Champions ended up just giving up and admitting defeat, realizing there was one opponent for whom none of them were a match.