Use 'superfan' in casual conversations or social media, rather than formal writing. My cousin is a superfan of that YouTuber!
Pro Tip 2/3
Intensity Level
'Superfan' implies a higher level of dedication than just a 'fan'. He's not just a fan of the show, he's a superfan who never misses an episode.
Pro Tip 3/3
Positive Connotation
Being a 'superfan' is generally positive, showing strong, but not extreme, enthusiasm. She became a superfan of the author after reading all of his books.