The Incredible Hulk has been a force to be reckoned with, able to make short work of most people and beings that he comes across. While this is highly dependent on which version of the Hulk he is whether it is Professor Hulk, Joe Fixit, Doc Green, Nul Hulk, or one of the many others. At the height of his power, Hulk is often referred to as one of the strongest beings in the universe.
Despite this, not every battle the Hulk engages in goes exactly as planned. He has had many unexpected defeats at the hands of unlikely foes and even defeated those that were seen as being more powerful at times.
10 Lost To: Batman
Yes, you read that right, the first entry on this list is DC's very own Batman. This took place in the 80's when Marvel and DC would occasionally have epic crossovers involving classic characters from each facing off.
This one saw Bruce Banner working for Wayne Enterprises when the Joker shows up and causes Banner to get angry and tear up one of Bruce Wayne's laboratories. Batman attempts to stop the Hulk but soon realizes his attacks have no effect. He eventually uses his sleeping gas on the Hulk, throwing it and following up with a kick so he inhales it. While this is an older version of the Hulk, it is crazy to think how he lost to someone so much physically weaker (although a great strategist) and that it happened as a result of sleeping gas.
9 Beat: Sentry
In the Planet Hulk storyline, the Illuminati decides the Hulk is a threat and exiles him from Earth to later return and get his revenge in World War Hulk. This is arguably one of the Hulk's strongest moments as he crushes any and all who are standing in his path.
He is able to defeat Doctor Strange, Iron Man in a Hulkbuster suit, The Thing, and many others. One who is able to equal him in strength is Robert Reynolds aka The Sentry. While initially reluctant to join the fight, he later came to put an end to the Hulk's rampage. Their powers proved to be very even and the fight resulted in the Hulk turning into human form and The Sentry very drained. The fight concluded in Banner punching Robert in his weakened state, unexpectedly winning the fight.
8 Lost To: Havok
In a very unusual face-off, the Hulk goes toe to toe with a member of the X-Men, Havok. After losing the military pursuing him, he thinks that he sees a former love interest of his, Jarella, the princess of sub-atomic green-skinned people. Despite this, he happens to be following Polaris also known as Lorna Dane, another member of the X-Men.
Things start to get heated when the Hulk follows Lorna and snatches her up. Havok pursues him with the intention to save Polaris, but later sees how outmatched he is, barely able to keep the Hulk back. Havok then decides to direct his plasma blasts at Hulk's brain, causing him to pass out. While Havok has proven to be quite strong, it is embarrassing for Banner just how easily he was able to incapacitate him.
7 Beat - Gladiator
One cosmic being of truly awesome strength is the Gladiator, originally part of the alien race known as the Strontians who rely on confidence to reach their full potential. These powers include heat vision, super speed, the strength to shatter a planet, and more.
Hulk and the Gladiator come face to face in the Incredible Hulk Annual 1997. It is a hard-fought battle between the two with Gladiator even using his heat vision to blow a hole in the Hulk's chest, almost reaching his heart. The Hulk then covers Gladiator's eyes so it rebounds on him. The fight ends when the Hulk throws him into a nuclear reactor, utilizing his weakness to radiation. While it does make sense, the Gladiator is of comparable strength to some others who have beaten Banner, so he could have been expected to do the same.
6 Lost To - Metal Master
While Magneto is the Master of Magnetism able to manipulate metal, he was not the only character to have that power. The Metal Master was an alien able to control the atoms and molecules of metals like the rest of his species in the Galaxy of Astra. He was later exiled from his planet for his attempts to take over and made his way to Earth.
Once there, he tried to convince the Hulk to join him and fought him when he refused. He was able to keep the Hulk at a distance using metal and even defeated him by trapping him in it. The Hulk was able to later defeat him with ease using a plastic gun which the Metal Master had no control over. Regardless, the fact that he was able to make such short work of the Hulk at first is crazy thinking of just how strong the character is now.
5 Beat - Thanos
Thanos is one of the cosmic beings who always puts up a fight against the Hulk, as was the case in Avengers: Infinity War. One exception comes in the pages of Marvel Zombies 2. Taking place 40 years after the original Marvel Zombies storyline, the series sees the few remaining zombies worrying about where they will get their next food source after exhausting the supply in their universe.
At this point, Zombie Thanos makes the mistake of accusing Zombie Hulk of eating more than his fair share, resulting in Hulk getting angry and clapping his hands around Zombie Thanos' head. For a character like Thanos, the Hulk is usually not a problem, but in this universe, the Hulk makes short work of him.
4 Lost To - Wrecker
The Wrecker is a fairly weak, easy to deal with villain as he mostly relies on his crowbar. Even though he was imbued with Asgardian powers, he is still not as much of a threat as most others. After the formation of the Wrecking Crew, he somehow managed to defeat one of the most powerful heroes.
The Wrecking Crew came face to face with the Hulk and the Defenders in a short-lived fight. While many would assume this was because the Hulk alone took them out, it was quite the contrary. The Wrecker used his crowbar to hit the Hulk once, knocking him out and defeating him in a humiliating way.
3 Beat - Thor
While Thor is the god of thunder and a being of immense strength in his own right, the Hulk is usually able to put up a fight. The two often face-off both in comics and on the screen, developing something of a friendly rivalry.
In the Marvel Cinematic Universe, one such fight came in Thor: Ragnarok in epic fashion. While stranded on Saakar, Thor was forced to fight the Grandmaster's champion who turned out to be none other than the Hulk. The Hulk put a beating on Thor for the majority of the fight, until Thor gained the upper hand. Despite this, the Grandmaster intervened by shocking Thor, causing him to lose the fight right as he was about to win.
2 Lost To - Circus Of Crime
In an even more bizarre circumstance than the Wrecker, the Circus of Crime achieved a strange victory. Led by the Ringmaster, the Circus of Crime originated from the 40's facing off against Captain America, though later reemerged in the 60's to face off against the Hulk.
While they do boast a wide variety of abilities and skills, they are not really superpowered in any way. In a weird turn of events, they manage to defeat the Hulk with a high-powered hose. The fact that he lost at all is extremely surprising, but how they did it just adds insult to injury.
1 Beat - Jean Grey
Jean Grey is another being often referred to as one of the most powerful in the Marvel Universe. As such, there are not many who can defeat her. Like Thanos, this defeat happens in the Marvel Zombies series.
Once the zombies returned to Earth, they faced off with Black Panther and the other survivors for a teleportation device there. The zombies later stopped fighting as they realized they were no longer hungry. Zombie Hulk, however, still had an appetite and ate many of the survivors as well as the Dark Phoenix.