The following are among the strongest hero characters from the Marvel Universe. I remember back when the Handbook of the Marvel Universe first came out in the 80s and it was partly designed to end disputes between fan-boys & role playing gamers about who was stronger. They actually had a section that identified the characters' strength levels. And the strongest ones had strength levels that were classified as Class 100 - meaning they could lift/press more than 100 tons! Of course, those included characters like Hulk, Thor, Wonder Man & Silver Surfer.
This particular issue, Marvel 2-in-1 Annual #7 introduced a really badly designed character (whom we now know is an Elder of the Universe, like the Collector, etc) named the Champion. He had basically taken the heaviest hitters of the Marvel Universe of the time for a boxing match.
In no particular order:
Hercules - deemed to be almost equal to Thor's strength levels. When Thor wasn't available, the Avengers either looked to Wonder Man or Herc.
We then have Ares, Herc's brother. As they are both Olympians, their strength levels are considered to be the same. Ares had been the Heavy Hitter for the Dark Avengers under Norman Osborn's leadership.
A-Bomb (I still can't be sure if it's a play on the word Abomination, who is one of Hulk's perennial enemies, or the word Atomic Bomb) - Believe it or not, this is supposed to be Hulk's long time pal and sidekick Rick Jones. Lately, he's been running around with Hulk and the Red Hulk. I would think that his strength level would be the same as the Hulks.
Thor - with 2 movies under his belt and an appearance in the Avengers, now everybody knows Thor is the Heavy Hitter of the Avengers. In fact, many consider him the only one (maybe the only other one is the Silver Surfer) in the Marvel Universe capable of giving pause to the Hulk. But then, that's not necessarily true as we are about to find out from this list.
Beta Ray Bill - I love this guy. First appeared in the classic Thor #337. Conceived by the guy who made fandom take notice of Thor - Walt Simonson. He was first thought to be an alien villain due to the way he looked but ended up with his own enchanted hammer called Stormbreaker - given to him by Odin himself, no less. Equal to Thor in every way, except that Beta Ray Bill is more level headed.
Thunder-Strike - Marvel is very good at introducing stand-ins for the iconic hero when s/he is taken out of the stories for a couple of years (like what's happening right now with Falcon Being the new Captain America and a female Thor!). So, back in the 90's, Marvel introduced the new Thor stand-in and he was really well received. I think in terms of strength, he was slightly weaker than Thor himself but still, you wouldn't wanna cross paths with him if you were a bad guy.
Doc Samson - a long time supporting character to the Hulk, always playing second fiddle to the Hulk but strong enough to take on the Hulk again and again in his attempts to capture the Hulk. Somehow, he didn't quite get the fan following as other characters enjoyed. Maybe it was his funky long green hair?
Gladiator - 1 of Marvel's many attempts at making Marvel's very own version of the Man of Steel (the others being Sentry and Hyperion, both of whom we'll see further down in this post.). First introduced in the Uncanny X-Men revival in the 70's as the field commander of the Shi'ar Imperial Guard. Recently, in the War Of Kings story-line, he was made to be Shi'ar's new Emperor after the death of their incumbent Empress Liliandra.
Valkyrie - a fellow Asgardian, so her strength level would be similar to Thor's, but more of a match to Sif (whom I didn't include in this list, along with the Warriors Three because she/they hardly ever appear outside of the Thor title.) Considered by many to be a stalwart member of the Defenders, along with several other heavy hitters on this list - Namor, Hulk & Silver Surfer..
Colossus - One of the founding members of the 2nd Generation of X-Men (which basically propelled the X-Men from being a cancelled title to the giant franchise it is today, thanks to Chris Claremont & John Byrne's ground breaking work in the late 70's/early 80's.). Basically, he is X-Men's heavy hitter.
The ever-lovin' blue-eyed Thing - Marvel's First Family's very own heavy hitter. For decades, fans had always clamored for a match between Hulk and Thing. Of course, the Thing, despite being very strong, is not quite in the same league as Thor or Hulk.Red Hulk - General "Thunderbolt" Ross, for decades, he had been a thorn on the Hulk's side, always hunting him down, now he is a Hulk himself. Well, I've read a couple of dozen issues of the Red Hulk but sad to say, I like him even less than before when he was just plain ol' Gen T'bolt Ross..
She-Hulk - Originally meant to be the female version of the major characters (Ms Marvel, Spider Woman, etc) but has since established her own place in the Marvel Universe. The game changing moment for me was really when she joined the Fantastic Four in the 80's during John Byrne's classic FF run.
Sasquatch - Another character whom I loved. Coming out of the Uncanny X-Men title (from Claremont & Byrne's creative juices) as part of Canada's very own super-team - Alpha Flight. I don't get to see this big hairy furball as often as I like these days.
Hyperion - Another version of Marvel's own Superman. Originally a character based in an alternative Earth where their version of the Avengers were called the Squadron Supreme (who were ALL a mirror images of DC's Justice League as imagined by Marvel.) I haven't read many stories featuring Hyperion but he's since been based on the main Marvel Earth recently.
Wonder Man - Another of the heaviest hitters in the Marvel Universe on the same scale as Thor. Under-rated & often ignored and he used to have a really horrible looking red jacket (Hmm, maybe that's why). I love his new ionic image.
Namor, the Sub-Mariner - one of Marvel's oldest characters dating back to the 40's. Now rebranded as a mutant (hence you can see his 'X' symbol below). King of Atlantis. Same explanation as for DC's Aquaman, the extreme pressures of the deep ocean basically mean that these Atlanteans have super tough skin and super strength when they are on land.
Red She-Hulk - I have to admit that I have not read any story with her in it yet but I do know that she's actually the Hulk/Bruce Banner's long-time love, Betty Ross (Huh???)! Yeah, I need a bit of catching up as to what happen to cause this development but off-hand, I'm gonna say I don't like it. The Sentry - Another one of Marvel's attempt at creating their own Superman in the 90s.He's so powerful that he literally ripped - yes, RIPPED, Ares the Olympian (see above) in two during the Siege. See this post to see what I mean.
Thundra - Marvel's version of the Amazons but from the future. A really tough chick that can single-handedly take on the big Green himself.
Skaar, Son of Hulk - This is another one of those characters that I have not read before. I guess it's just cause I get put off by so many Hulk clones/rip-offs/derivatives like Red Hulk, Red She-Hulk, A-Bomb, etc. So I really have no interest to read his stories at all.Silver Surfer - Formerly the herald of the planet-eater Galactus. I just love this guy. He doesn't look it but he's so strong and powerful he could take on ALL the Avengers alone and come out on top if he wished.