There are lots of frightening things in Naruto, but none that scare the citizens of Konohagakure like Orochimaru. While there are things like giant animal spirits and ninja who can control others using their shadows, Orochimaru embodies a completely different type of horror. Much like Freddy Krueger, who terrorized the nightmares of children on Elm Street, Orochimaru horrified the village by kidnapping its citizens and performing experiments on them. However, there's something even more frightening about having a snake-person snatching people from off the streets. Freddy Krueger mainly stuck to certain people, but Orochimaru can go anywhere and take anyone.
He started out much like Naruto, an orphan living in the village. However, he was much more intelligent and was considered a genius by many. He was talented and could have accomplished great things, but it seems the death of his parents triggered something within him, turning him into an out and out sadist at an early age. Tsunade even says as much. The signs were there.
For example, Orochimaru wanted to kill a bunch of orphans that he, Tsunade, and Jiraiya found as a "mercy killing," whereas Jiraiya wanted to train them. Orochimaru staged the attack on Kumogakure by the Eight-Tails. What's even more terrifying is that he was almost the Fourth Hokage. Luckily for everyone, Hiruzen recognized the evil in Orochimaru's heart, and named Minato as his successor instead. Unfortunately, this also led him to kidnap sixty children and perform experiments on them. Much like Krueger, who delights in torturing the youth of Elm Street, Orochimaru takes a twisted kind of revenge on Konoha by snatching its kids. Except Freddy will just kill you, Orochimaru will make you as monstrous as he is.
Orochimaru is a manipulator who gets others to do horrible things for him, moving only for selfish reasons, not caring who he hurts in the process. He looks down on the fragility of human life and does everything he can to overcome it for his own sake. He experiments on people to see what the human body is capable of withstanding and then applies his grotesque findings to his own body. Orochimaru's body is as twisted as he is, from a disgusting snake tongue to the eerie flexibility, not to mention all the other actual body horror elements to his character. Despite not experimenting on others, Freddy is much the same, gaining a God complex akin to Orochimaru's from his seeming immortality in the realm of dreams.
Orochimaru's also charismatic, which allowed him to garner followers and acolytes. Even then, he doesn't care what happens to them, though he does show some interest in their development. Despite this, he shows no emotion when one of them is killed. He just moves on to the next one.
Orochimaru is arrogant and uncaring. He believed he was above death, attacking without restraint or care for his own life. He never once thought about he was affecting others or how his experiments were cruel. He reveled in the fact that he could do so much without anyone stopping him, though they didn't try. He's mentally and emotionally manipulated people like Sasuke, who viewed their home as corrupt and unjust.
Freddy Krueger haunted the dreams of children and teens who lived on Elm Street, taking revenge against those who had a hand in his death before he became what he is today. He was a serial killer in life and in death, kept alive through the town's fear. It was the thrill of killing that brought joy to Krueger, a sadistic streak he shares with Orochimaru. But, for him, it was the potential to find a new host body and to extend his own life. He wanted to surpass death, no matter the cost. He would extend the pain caused to his victims, and he had no problems experimenting on children. That makes him just as terrifying as Krueger.
