One of the most endearing and consistent aspects of the Dragon Ball franchise has been the relationship between Piccolo and Gohan. Their bond has been most noteworthy for being a key piece to Piccolo's redemption arc and transition from villain to hero. Ever since he sacrificed himself to save the half-alien boy, Piccolo has served as a father figure to Gohan in ways Goku never was and maybe never could be.
However, even though Gohan always brought a more caring side out of the Namekian, even in the Saiyan's adulthood, that is not to say that Piccolo never did anything to the boy that showed shades of his former evil self. Perhaps even stranger than an alleged "father figure's" cruel acts is that along the whole way, no one else seems to care.
10 Not Caring To Save Him
At the very start of Dragon Ball Z, Gohan gets kidnapped by his long-lost uncle Raditz. Piccolo offers his sworn enemy Goku some help to find him, but it has nothing to do with a change of heart or wanting to save Gohan.
Piccolo point blank admits it before he and Goku embark on their journey. He doesn't care about Goku, his friends, or his son. He just could not stand the thought of some alien warrior conquering the world before he does. Perhaps because Goku was running out of options, he didn't bat an eyelash at Piccolo's comment.
9 Making Gohan Fatherless
During that same Saiyan Saga, it was during that fight against Raditz that Piccolo's Special Beam Cannon put a hole through both the Saiyan invader and his brother, resulting in not only Goku's first death in the series but also making Gohan a fatherless young boy.
While it was a necessary means to defeat a common enemy, Piccolo is never confronted by Goku's friends after the fight about directly causing the death of their Z-Fighter leader. The Demon King descendant never has to answer for this, especially since it's clear that he had no problem with killing Goku, killing both of his enemies in one flail swoop.
8 Kidnapping Gohan
Furthermore, what is even worst than Piccolo making Gohan a fatherless boy within the blink of an eye, he decides to kidnap the boy under the impression only he has the credentials to train him before the Saiyans arrive. He also does so without much of a fight.
Granted, Piccolo did promise that he would take the child regardless of what the Z-Fighters thought and was willing to do so with brute force if necessary but to see it happen without much of a fight from his supposed caretakers was troubling for everyone involved. Not even Krillin or former World Martial Arts Tournament winner Master Roshi budged.
7 Leaving Him Alone For Six Months
Speaking of Piccolo training the Saiyan half-breed, the master manages to traumatize his student within a span of about five minutes. First, upon waking the boy up after he was knocked out by Raditz earlier, he coldly tells him that his father is dead and he must prepare to have his first fight against Saiyans who will be invading the earth in a year.
Then, as if that wasn't bad enough, he immediately abandons the boy for six months, thinking that leaving a four-year-old boy in the wilderness to fend for himself will toughen him up. Nevermind the fact that he's never been so much as without his parents before and he's an infant surrounded by rabid animals and dinosaurs.
6 Brutally Training Him For Another Six Months
Miraculously, when Piccolo returns in six-months, Gohan was not eaten by a dinosaur before they could begin their training properly. However, when they do decide to start physical combat training for the next six months, Piccolo does not go easy on the boy at all.
It's understandable, knowing that the Saiyans won't go easy on Gohan when they finally fight, but again, Gohan had never been in a fight before. He never so much as scraped his knee off a fall before, and without warning or an introduction, this four-year-old gets bruised, bloodied, beaten, and nearly drowned by a grown man.
5 Training Him Just As Brutally In Super
Fast forward to Dragon Ball Super for a moment, where Gohan, in hopes of getting back to his old self, gets Piccolo to train him again. However, in doing so, Piccolo does not hold back in training him just as brutally as he did when Gohan was a kid. And since Gohan is a full-fledged adult at this point, Piccolo probably fought even harder.
This led to the Namekian strangling Gohan to the point of him passing out in their grueling training. Even though it works in helping Gohan reach his Ultimate form again, no one takes umbrage with Piccolo nearly making Pan a fatherless daughter!
4 Throwing A Baby At A Mountain
With all of this talk about Gohan's training, it is also worth noting how the two initially introduced themselves to each other. Moments after killing Gohan's father and kidnapping him, Piccolo takes Gohan to a barren wasteland. Before stranding him for six months, he tries to test a theory that Gohan's powers are unlocked when he's in emotional danger.
He tests this theory by chucking Gohan - an actual baby - at a mountain. Sure, Piccolo's theory proves right when Gohan's emotions activate a ki blast to destroy the mountain, but if he was wrong, that could have ended really, really badly for Gohan.
3 When Piccolo Cut Off His Tail
When he sees Gohan become a Great Ape for the first time, he destroys the moon and cuts off the boy's tail. Reasonable reaction.
This entry is not quite as "terrible" - especially compared to these other entries - when Piccolo mostly did so for the greater good of protecting himself and everyone around him who could be affected by a feral Gohan. This mostly fits the bill in that no one cared afterward. No one really reacted much upon seeing Gohan without his tail a year later, but to be fair, the Z-Fighters had bigger issues to worry about in the form of the invading Saiyans before them.
2 Snapping At Gohan For Being A Kid
In Piccolo's defense, Gohan's whistling was enough to pierce any Namekians sensitive ears, as viewers later learned at the end of the movie. But in the Lord Slug opening scene when Piccolo snaps at Gohan for singing and dancing, it essentially yells at the boy for doing something that he cannot help but do at his young age.
Kids sing and dance all of the time and yes, it's annoying, but ear piercing aside, Piccolo's reaction might be considered an overreaction for the average audience member watching.
1 Calling Gohan A Failure
When it finally came time to fight the Saiyans that he and Piccolo desperately trained for a year to face, Gohan froze in his steps. Froze in a "fight or flight" way, and when Piccolo ordered Gohan to shoot a blast at an incoming Nappa, the boy ran away instead.
Piccolo harshly calls Gohan a failure, acts as if their year of training was a waste, and suggests that Gohan run off back home to Chi-Chi. None of the remaining Z-Fighters disagree. For all of the time that the two spent together, regardless of how much Gohan regressed in the past year, that may have been a little harsh.