"Diehard fans" refers to people who are extremely dedicated, loyal, and passionate about someone or something. They support and follow them unconditionally, even during difficult or challenging times. Full definition
I'm finding it hard to recommend Anima: Gate of Memories to anyone outside of diehard fans of the IP and I don't know a single person that falls into that category, so I can't really recommend it to anyone. (metacritic.com)
A little innovation, however, could have totally sealed the deal for diehard fans of the Bejeweled games. (darkstation.com)
Coasting on the devotion of diehard fans who remember the back stories, this latest installment suffers from franchise burnout and never breaks a sweat. (joyceschoices.com)