What would Snape's Boggart be?
The shape of Snape's Boggart isn't revealed in the books or movies, but there are hints throughout the series about his worst fears.

One of the most interesting aspects of the Harry Potter series is the Boggart, and while most of the main characters' Boggart shapes appear in the Harry Potter movies and books, this was not the case with Severus Snape in this way. A boggart is a shape-shifting creature that takes on the worst fears of those who confront it. It was introduced in the third film, Harry Potter and the Prison of Azkaban, when audiences witnessed the Boggart's portrayal of many characters. A notable exception is Snape, whose boggart has never been revealed despite being a key figure in Harry Potter due to Snape's character arc from villain to hero.
It's interesting to see what the Professor's Boggart would look like, especially given that viewers learn about Snape's past relationship with Harry's parents throughout the film. One theory is that Snape's Boggart reminded him of the death of Harry's mother, Lily, and the fact that he would never have the woman he loved. However, both of these fears had been fulfilled in Snape's life. So it's unlikely that Snape's boggart in Harry Potter was something he'd already experienced and had. Live each day as if Snape felt guilty about Lily's death.
Harry Potter Already Revealed Snape's Perfect Boggart

Clues to Snape's possible Boggart form are still in his past, but not based on his feelings for Harry's mother, but possibly through his relationship with Harry's father. Harry Potter establishes the relationship between Snape and the Marauders' years at Hogwarts through flashbacks. Although the animosity between James and Snape was mentioned several times in the Harry Potter books, moviegoers rightly witnessed that the reason behind Snape's hatred for Harry's father was Harry Potter and the Order of the Phoenix.
When Harry was learning Occlumency with Snape, he stumbled across one of the professor's worst memories without his consent. In this memory, he watched his father and Sirius bully Snape, insult him and cast spells on him. The bullying and humiliation Snape suffered due to the Marauders was likely his Boggart, as it was one of the factors that eventually led Snape to join Voldemort's side and fall out with Lily. It's one of the reasons why Snape always seemed to hold a grudge against Harry himself.
What Was Snape's Boggart Before Hogwarts

However, Snape only saw James and his friends during his tenure. Time at Hogwarts. What was the boggart of his childhood? In Harry Potter, boggarts can change their appearance depending on who is in front of them, so it's likely that characters have different boggarts at different stages of their lives. Readers learn about Snape's childhood and his relationship with his Muggle father, Tobias Snape, who is described as a sadist. Snape grew up with a violent father and was often lonely, friendless and neglected by his parents. So if he met a boggart as a child, the creature could have taken on his father's likeness.