Gohan is definitely one of the most popular characters in the entire Dragon Ball franchise. As the son of Goku, he definitely lived up to his name as the hero fans expected him to be, even surpassing Goku at one point in time. While he has been responsible for many of the series's most impressive feats, he's also done some pretty terrible things, most of which altered the trajectory of the entire series.
10 Made a Mess Out of His Birthday Celebration
Before the Cell Games began, Gohan celebrated his eleventh birthday, and much to Chi-Chi's disapproval, he was already following in his father's footsteps of becoming a "delinquent". It was nice to see Gohan, Chi-Chi and Goku, Ox King, and Krillin gather to celebrate the young half-Saiyan's life, but when it came time to blow out his candles, the young Super Saiyan created a typhoon that smashed cake into everyone's faces. After getting icing up her nose, Chi-Chi was infuriated, but all Gohan could do was laugh. In the end, she decided to forgive him, but he should've known to hold back his strength for the sake of his poor mother... And the cake!
9 Allowed Another Woman to Kiss Him
Despite losing his knack for fighting in Dragon Ball Super, Gohan showed fans how great of an actor he was after stealing the lead role of a Great Saiyaman from the famous actor Barry Khan. After bonding with the actress Cocoa, she kissed him right on the lips, and Gohan didn't do a thing to stop it. Despite not being as strong as he was back when he fought Super Buu, Gohan should've still possessed the reflexes to dodge that kiss if he really wanted to. Plus, after the kiss, he blushed far more than a married man should in that situation.
8 Got Universe 10 Erased
Going into the Tournament of Power, fans knew that the Z-Fighters would be forced to eliminate the other competitors, leading to the erasure of entire universes. While this was expected from fighters like Goku, Vegeta, Frieza, and even the Androids, it was hard to believe that Gohan could knock fighters out of the arena knowing the end result. During one of Gohan's major battles in the Tournament of Power, he managed to eliminate Obuni, who happened to be Universe 10's final warrior. Upon falling out of the ring, Obuni dropped a locket that revealed a picture of his wife and newborn, a family situation that Gohan could definitely relate to after just having Pan, and yet he showed no remorse with the revelation that he was responsible for the death of this infant. Sure, Obuni and his family were revived at the end of Dragon Ball Super like all the other universes, but at the time, it was jarring to see such a merciless version of this family-friendly scholar.
7 Almost Destroyed the Planet as a Great Ape
Piccolo wasn't around when Goku had a tail, so he had no idea that the young half-Saiyan would turn into a Great Ape upon looking at the full moon. As a Great Ape, Gohan loses much of his rationale as his primal urge to kill takes over. This doesn't change the fact that the first time he turned into a Great Ape, he could've destroyed the entire planet, with Piccolo being the only one at the time who would've been able to stop him. Despite not really knowing what he was doing, Gohan nearly turned the Earth into a nice parking lot for Vegeta and Nappa.
6 Destroyed Chi-Chi's Freshly-Plowed Field
Seeing Goku and Gohan actually spar together had become a rare treat as Dragon Ball Z went on. It wasn't until Dragon Ball Super got well underway that fans got to see father and son trade blows until Chi-Chi stopped them, and with good reason. They managed to not only decimate their freshly-plowed field, but also caused an entire side of a cliff to come crashing down onto the surrounding forest. Just imagine how many animal lives had been lost from such an environmental disaster, as well as how many years Chi-Chi lost from the stress alone. Sure, Goku is definitely responsible for this as well, but by now, fans expect no less from him. Gohan's the one who inherited his mother's propensity for common sense, but with that Saiyaman suit on, he just really got into character.
5 Didn't Immediately Defeat Super Buu
Despite having the strength to destroy Super Buu in an instant, Gohan chose to take his sweet time pounding Buu into the dirt, giving him the chance the absorb Gotenks and Piccolo, which turned the tide of battle completely. If Gohan would've just taken Buu out from the start, fans wouldn't have gotten Kid Buu, which meant that all those planets Kid Buu managed to destroy would have been spared. Unfortunately, that also would've meant that Goku and Vegeta would've stayed dead, but at least Fusion Reborn would be canon.
4 Gave Cell an Opportunity to Turn the Tide of the Battle
After watching Cell and his minions torment his friends, Gohan wanted to make Cell pay after he became the universe's first Super Saiyan 2. He possessed more than enough power to destroy Cell in a single blow if he wanted to, but because he wanted to make Cell suffer, Dr. Gero's finest creation was able to put Gohan in a bind, threatening to self-destruct. Although Gohan managed to defeat Cell at the end of the day, it was at the cost of his father's life. If Gohan had just taken Cell out like Goku advised, he would've actually gone through puberty with his father by his side to have all those uncomfortable conversations that Chi-Chi apparently skipped out on.
3 Didn't Attack Nappa After Krillin and Piccolo
During the fight with Nappa, the Z-Fighters realized how outmatched they were, and decided that the principles of honor didn't apply with this battle. As Nappa rushed to deal the killing blow against Tien, Piccolo hit him at Krillin, who then hit him towards Gohan. Both of them relied on Gohan to finish Nappa off with an attack of his own, but Gohan became so paralyzed with fear that he failed to attack, eventually leading to Piccolo's death. Of course, if Piccolo hadn't died in this fight, there wouldn't have been a need to even go to Namek in the first place. Frieza wouldn't have heard through the Scouters that Namek was where he could go to attain immortality, and the Namekians wouldn't have known the terror of Frieza's forces.
2 Neglected His Training
Perhaps one of the worst things Gohan could've done was neglect his training. When Vegeta voiced his concern at Gohan's power decrease during his fight with Dabura, fans eveywhere did the same. If Gohan had only kept up with his training, Dabura would've been killed in a matter of seconds, and Majin Buu's resurrection would've failed. In Dragon Ball Super, he became a walking disgrace after having his power drop so low that he could barely sustain a simple Super Saiyan transformation. Gohan had all the potential to excel far beyond Goku and Vegeta, and yet he never even got a new transformation in all of Dragon Ball Super. If he hadn't neglected his training so much, Goku and Vegeta would finally be able to take a day off every once in a while.
1 Let a Little Kid Shoot a Gun
Perhaps the absolute worst thing Gohan has ever done was during Battle of Gods when he encouraged Mai to empty an entire pistol at him. Sure, he was able to deflect the bullets with only one finger, but there was so much wrong with this. Although he assumed that the gun was a fake, it was wrong to encourage children to play with weapons anyway. If he wasn't so intoxicated in the first place, he wouldn't have been in such a mood of bravado. He also managed to ricochet one of the bullets right into the leg of his pregnant wife! This idiot could've killed his own unborn child! Without Pan, it'd be very difficult for fans to argue that Dragon Ball GT is canon. Thanks a lot, Gohan...