In a shonen anime like My Hero Academia, many of the main characters are in their teens, meaning they need parental figures to protect them, guide them, and support them as they grow up. While there are a few notable mother figures in My Hero Academia, like Inko Midoriya and Nana Shimura, the anime focuses even more on father figures, men who either supported their own children or served as a father figure to someone else.
The anime has a notable collection of father figures, biological and otherwise, who range from abusive monsters to exemplary parental figures, and everything in between. Sometimes, the characters might not consider themselves father figures first and foremost, but that is still one of their major roles in the story all the same. Some of those men wouldn’t call themselves parental figures, but for certain youths in their lives, that is absolutely what they are.
The supervillain All For One is the single worst father figure in My Hero Academia for many reasons, including the fact he’s a criminal mastermind who only ever hurts people. As for his parental role in the story, All For One was the one who adopted Tenko Shimura after that traumatized boy killed his entire family, then started reshaping Tenko into a true villain, starting with a new name.
All For One presented himself as a caring foster father to Tenko/Tomura, including giving that boy his own bedroom, but it all came with serious string attached. The symbol of evil did that, not to help a child in need, but to mold him into an heir, a process that included aggravating rather than soothing Tenko’s mental anguish. Also, while All For One sometimes spoke fondly to Tomura and praised him, he saw Tomura as a tool and living vessel, not a true son.