The biggest blunders made by a protagonist in animation.

[kafalucysnow]

Simple rule of life. No one is perfect. People make mistakes, including those who have the role of the hero/heroes. The ones that stand out to me for the moment:

1. All versions of Spider-Man: Granted this is during his short lived stinct as an entertainer, he makes the decision to let a burglar run past him (most versions because he is indifferent whereas Spectacular he does it to get even with the fight promoter for cheating him out of money). As a result, his Uncle Ben is gunned by the same guy.

2. The Legend of Zelda "The Moblins Are Revolting": Long story short. Ganon is trapped in an energy bubble. A bubble that only the Triforce of Power can destroy. So Link, being the goofball portrayed by the cartoon, tosses Ganon around like a ball and nearby the Triforce.

And yet, Zelda chooses not to fire him or lock him in the dungeon. Go figure.

3. The Real Ghostbusters "X-Mas Marks the Spot": The Ghostbusters remedy this one, but still messed up in the first place regardless. The episode begins with them on a drive only for a timewarp to old England. During their time there, they successfully bust three ghosts. The ghosts who are suppose to rehabilitate Ebeneezer Scrooge, unfortunately.

As a result, Christmas through time is rejected by society thanks to Scrooge's book "A Christmas Humbug". Needless to say, Egon is successful in retrieving the 3 Ghosts, and Christmas is restored, but way to mess up guys.

[ellie.]

Omi in the series Finale of Xiaolin Showdown. His plan to make Chase Young a good guy had a huge flaw that screwed everything up. It consisted of him freezing himself for eighty years to retrieve the sands of time that his older self hid. However because he Froze himself he created a time paradox and older Omi never got the sands of time because there was no older Omi. His blunder caused him to land in a world where Jack Spicer rules.

[Hibachi]

Gargoyles: Goliath only choosing to take Hudson with him in part 1 of 'Awakening'. Even if he was still doing what would be in the best interest of the clan without realizing he'd been betrayed by his true love, his mistake in only taking one other Gargoyle along with him resulted in most of the clan (with the exception of the trio, Bronx, and Demona) getting slaughered.

[Go Yankees!!!!!]

Everybody who finds some ancient talisman or map that can unleash a force of incredible power, and then doesn't destroy said talisman or map. Most recent example I can think of: The Secret Saturdays and the Kur Stone. The stone is a map to the tomb of a being capable of conquering the world, but he won't wake up unless someone wakes him. So, reduce it to dust and there's no problem!

[gc349]

At the end of The Spectacular Spider-Man episode "Intervention", Spidey tries to destroy the alien symbiote by putting it in a freezing chamber. Having a scientific background, Peter should have easily known that wouldn't work since it's survived the cold vacuum of space. This, of course, leads to the symbiote bonding with Eddie Brock, becoming the vengeful Venom. And he would have had his revenge for sure it the symbiote wasn't stupid enough to be tricked by Spidey, claming he wanted to bond with it again. It should have sensed his deceit and not separate from Eddie. It's surprising Peter never used its true weakness of sound against it. Surely, that would have been the better option.

["get over it"]

In DBZ Vegeta allowed Cell to reach perfect form, letting his pride endanger the entire universe. Gohan also made the mistake of toying with Cell to make him suffer, instead of right off finishing him.

[Kelsang]

Chihiro gasping at the frog would be a big one in Spirited Away. None of the other stuff on the bridge was weirder than a talking frog? :anime:

[Henry 112]

There's a bunch, but I'd need to sit down and think about this one.

One I recently watched was in Captain N: "Videolympics".

The N Team seriously thought Motherbrain was magically going to give up if her rag tag team of misfits beat the N Team.

Seriously ...

[DLillian]

The Z Soldiers, after receiving the warning from Future Trunks about the impending invasion of the Androids in 2 years time, stupidly opt to train for those 2 years so they'll be ready when the Androids come, instead of going along with Bulma's decision to take out Dr. Gero before he ever gets the chance to invent the Androids. Is flexing your muscles really so important that you have to put the entire planet in danger just to show how hard you are?

[goddess n]

I have a tricky one. It comes from the first Fullmetal Alchemist Anime...
[spoiler]Roy Mustang's revenge on Pride/Fuhrer Bradley. We learn of Roy's promise to Hughes that he follow the right path to be a great man (meaning no revenge, in a scene where Edward is all for it). However, what does Roy do? He avenges his best friend's death by killing Bradley for revenge! He succeeds in his plan, but at the cost of an innocent child's life. Evidently, Selim Bradley's devotion to his father was something Roy didn't consider in his plan. The guy definitely had too much 'grief=rage=revenge' on the brain (and this is not some Anime1 OOC nonsense: the manga's Roy was also too easily drawn to revenge against the murderer of his friend).
However, playing Devil's advocate, What choice did Roy have? His earlier ambition of rising up the ranks was now a pipe dream. The list of allies with enough power to take down a Homunculus was thin: Izumi was coughing up blood. Armstrong had to protect Roy's besieged subordinates. Edward had to deal with rescuing his brother from Dante. So Bradley was Roy's job. Besides, the clock was ticking on the invasion of Drachma, which Bradley assigned Roy to commence. Now that he knew the reasons for the wars, Roy could not let another Ishbal Massacre take place.
So what we have here is a 'darned if you do/darned if you don't' situation. Bradley had to go, and his destruction ended the Homunculus' control on the country. However, with the effort Roy put in trying to redeem himself for past deeds, to end up committing selfish revenge- and to have that path lead to a child's death- must have been a heavy blow to the man (hence his situation in Shamballa). One more mistake he will always regret, for all the good it did.[/spoiler]