While Hollywood frequently casts adult actors in teenage roles, the "Harry Potter" series largely adhered to age-appropriate casting, with one notable exception: Moaning Myrtle, whose full name is Myrtle Elizabeth Warren.
British actress Shirley Henderson, who portrayed the character, was 36 years old when filming began for "Harry Potter and the Chamber of Secrets," yet she was tasked with embodying a 14-year-old Hogwarts student. Henderson recently reflected on her casting process in an interview, calling the entire situation "a bit ridiculous," but acknowledging that it led to her becoming a beloved and iconic character for fans.
Henderson revealed to The Independent that the casting director encouraged her to audition but specifically advised her "not to mention her age." She admitted she initially had no concept of "Harry Potter" until her sister, who was living with her at the time, reminded her of the franchise's popularity, prompting her to give it a try. Despite this, she remained concerned about portraying a 14-year-old girl.
In another interview with Radio Times, Henderson laughed, recalling that when she went to the audition dressed in a "school uniform"—a white shirt, black skirt, and ponytail—she found the whole thing "absolutely ridiculous." After completing the audition, she assumed nothing would come of it, only for the production team to contact her months later and formally offer her the role.
Reflecting on the filming experience, Henderson noted that Moaning Myrtle, as a ghost, inherently had a hazy, ethereal visual effect, which ironically helped mask the age difference.
"Moaning Myrtle is essentially an old soul in a young body, and with all the mist constantly floating around on screen, you don't really scrutinize my face, so it definitely helped me get away with it," she explained. She also revealed that because Moaning Myrtle often appears in isolated settings, most of her scenes were filmed alone in front of a green screen, seemingly echoing the character's sense of isolation.