When Harry Osborn got his first bike, some boys stole it from him. His father took it back only to break it into pieces in front of his son and tell him that this is what happens to the things that he can't guard. Years after, because of his toxic father, Harry started to use drugs and it is part of the reason why he became the second Green Goblin. And what Norman went on to do makes him king of this trope.
In American Son Story, we learn Norman supposedly had sex with the then-current girlfriend of what we later learn was a clone of Harry. He supposedly knocks her up, and made Harry-clone think the offspring was his. Then he decided he was going to have the kid raised up as a new Goblin. Then when his public ratings were starting to tank, he decided he'd have Harry-clone "accidentally" get killed in the line of hero duty to drum up sympathy for himself. Fortunately, the last one failed and everything else was quickly retconned. Norman didn't knock up the girlfriend and Harry-clone was the baby daddy, but he's made himself a good solid candidate for Worst Father Ever.
Norman's own father was also abusive to him. It must run in the family.
While Harry was going insane as Green Goblin II, it was heavily implied that he was grooming his son to be just as much of a maniac as him. We see him strike his son, who was playing with a toy. Harry immediately regretted it afterwards and he's never seen getting physical again, taking his son in his arms to hug him as they both cry. But this is still abuse.
The worst part is that after the events of Last Remains it's revealed Norman cared so little for his son that he offered his soul in a Deal with the Devil with Mephisto, which is implied to be the reason for his horrible life and tragic death.
Otto Octavius’s father was incredibly abusive and his mother was overbearing. It’s a small wonder Otto turned out like he did given his terrible upbringing.
Mary-Jane Watson's father, Philip Watson, was a successful college professor who wanted to become a writer. Problem was he wasn't any good at it. He kept trying though. Meanwhile, bills for his daughter Gail's ballet lessons were getting more and more expensive, until one day Philip lashed out at his family, blamed them for his inability to write, and struck his daughter. His wife instantly took her kids and left him, being forced to move around from one unsupportive relative to another afterward. And then Philip went and sued her for desertion, before severing all ties with her and his daughters anyway.
Oh, and there's Black Tarantula, Spider-Man's ex-enemy, who, in the '90s, tried to take his son from his ex-wife, both of whom were under the protection of another criminal. He attacked that criminal's headquarters alone and defeated everyone who got in his way, including Spider-Man. However, when his ex-wife reminded him how his father had destroyed his childhood by forcing him into training and asked if he wanted the same for his son, he just walked away, leaving them alone.
Darkdevil from Spider-Girl, by a gambling alcoholic uncle. Not to be confused with his other uncle.
One of Ben Reilly's girlfriends, Elizabeth Tyne, who decided to become a Self-Made Orphan. Made worse in Spider-Girlof all universes, where it's implied that after turning herself in, Elizabeth spent the rest of her life in prison for killing the jerk. Oh, and her son ends up being (physically) abused by her family, too.
Trouble, before it was thrown into Canon Discontinuity, implied that Aunt May's father was abusive to her and her mother and feared his reaction to her being a teenaged mom to what would've been her son/"nephew".
Cletus Kasady, the host of the Carnage symbiote, has serious issues with this. At least one of his parents was abusive. He said once that his mother tried to kill him, but his father saw this and killed her. However, another time he said that his father killed his mother, when he was trying to kill him. Possibly his grandmother was that same kind of person. For both father and grandmother it didn't end well.
Eddie lost his mother at childbirth and his father, Carl, resented him for it. When Eddie accidentally killed the child of a neighbor, Carl used most of his money to cover it up, further resenting him. And when Eddie lost his job due to the Sin-Eater incident, Carl disowned him. When Eddie's former wife, Anne, mysteriously gave birth to Dylan, Carl took possession of him at Anne's insistence and abused him when Eddie showed up again. The symbiote put him in his place by leaving him in the desert.
Flash's father, Harrison, was a member of the NYPD, but the stresses of the job led to him turning to alcohol and abusing his kids, especially Flash.
Films
Implied in the Spider-Man Trilogy. Mary Jane's father is heard yelling at her, and we hear him mentioned, but we never lay eyes on the man. Of course, he's abusive so it's no great loss that we don't know anything more about him.
Western Animation
In The Spectacular Spider-Man, Norman Osborn barely conceals his contempt for his son, Harry. This manifests in snide criticisms about his son's issues, hobbies and successes, and also in blatant, stunningly passive-aggressive displays of Parental Favoritism towards Harry's best friend, Peter Parker, when both boys are present. That is, when Norman isn't dismissing Harry and ignoring him entirely in favor of his job. Harry's mother does this too, not even verbally acknowledging him when he greets her. As a result, Harry has... issues.
