Many underestimate the importance of a strong father figure in forming a child's dietary habits. Dads tell children to keep their elbows off the table and to not chew with their mouths full of food. If Hannibal had a member of his family to consistently tell him to keep his napkin on his lap and to not eat people, he might have been living it up in a nice duplex on Staten Island, supporting his wife and kids as an insurance salesman instead of being chained up in prison/eating census takers.
Kidnapping is bad. Most people should know that. Kidnapping people and setting them through mazes where the only path to survival involves near-death self-mutilation is similarly bad. If Jigsaw's dad had been more present and told him that, he could have could have become a famous funhouse architect or a very effective parole officer.
The Terminator was a villain of circumstance. He never had a father computer to tell him that being an assassin sent through time to kill the leader of the human resistance is actually a really mean and hurtful thing to be. A better father might have coded into his mainframe so that it is not okay to be a part of the robot coalition set on bringing about the destruction of the human race.
The Shark from Jaws obviously did not have a daddy shark to teach him some of the most important shark-hunting tips: Cape Cod is the worst place to try to find food because it's just so crowded and touristy in the summer, skinny dippers have no nutritional value, and never eat a pressurized tank: they are just too easy for people like Roy Scheider to shoot and thus explode you with. If the shark had a dad to teach him these simple rules, he could have terrorized a small fishing village in Polynesia for as long as his ginormous shark heart desired.
Fathers and Daughters have a very delicate yet potentially beautiful relationship. Good fathers know the importance of letting their daughters know just how beautiful and special they are. They must protect their little girls, but also help imbue them with the confidence necessary to face the world. The Wicked Witch of the West must have had a tenuous relationship with her father from which she never learned to appreciate her green skin or overcome her hydration issue. She could have been such a nice witch.
Although sex can be an awkward topic of conversation, it is an important one. Dads are a great source of knowledge and advice for the male side of intercourse and romance. The facehuggers didn't understand the nuance of interpersonal relationships and didn't know any better than to latch onto the faces of astronauts and impregnate their stomachs without consent. If the facehugger had a dad to teach it how to properly ask someone on a date, Alien could very well have been a movie about John Hurt's crazy interstellar romance.
The string of natural catastrophes that plagues the characters of the Day After Tomorrow shows obvious signs of a lack of empathy. It just never had a stable disciplinarian in its home growing up to teach it the consequences of its actions. If it had a strong father figure to teach it right from wrong and the appropriate times to freeze the northern hemisphere of the world and set packs of vicious wolves throughout New York City, the series of Armageddon-level storms could have been an ally or even a love interest for Jake Gyllenhaal.
One of the most important things that dads can do for their kids is to tell them that Jews, the Roma, the LGBT community and all other non-Aryans are in fact not a cohesive plague plotting to rot the world to its core, but rather just a group of people, like you and me. If Hitler had learned this lesson, he might have had a successful career as a Charlie Chaplin stunt double.