One of the most intriguing creatures in the Wizarding World of Harry Potter is the Boggart, a shapeshifter that takes the form of whatever a person fears most. Much like Hogwarts houses, wands and full-bodied Patronus charms, the form a character's Boggart takes can say a lot about them.
Source:https://www.cbr.com/harry-potter-character-boggarts-explained/