The Fat Friar was once a Hufflepuff student who was taught by founder and Head of House, Helga Hufflepuff. After his unfortunate demise long after leaving Hogwarts, the Fat Friar found himself back at Hogwarts as the House Ghost for Hufflepuff.

The Fat Friar's name is unknown from his living life, but he attended Hogwarts School of Witchcraft and Wizardry during Helga Hufflepuff's time at the school and was taught by her directly. At the school, he was sorted into Hufflepuff and was thought to have remained at the school for all seven years.

After graduation, the Fat Friar joined religious life (Catholicism) and practised mendicancy. It cannot be confirmed whether he officially gained the rank of 'Friar' while practising his relgion, or if this name was simply a nickname after becoming a ghost.

The Fat Friar was said to be the kindest of men with all those Hufflepuff qualities. Unfortunately, his good heart and efforts in healing people by using magic (poking them with a stick), along with conjuring rabbits from the communion cup, would be his undoing. Senior members of the religious order grew suspicious over these actions, and eventually his magic would see him executed.

After his death, the Fat Friar returned to Hogwarts and became the Hufflepuff House Ghost. He enjoyed supporting and welcoming all the new faces to the house, and he still held onto those Hufflepuff traits he had long before he died. The Friar seemed to have good relationships with everyone he came into contact with and was seen frequently talking or passing information on with students or other ghosts. He even did his best to support Peeves the Poltergeist, who caused nothing but trouble, but his attempts rarely worked with the other ghosts, as Peeves simply couldn't be trusted.