The convention is organised by SFera, Zagreb's science fiction society, and will once again offer a packed programme for fans of science fiction and related genres, the organisers said in a statement.
The event will mark the first visit to Croatia by actors from the Harry Potter films, which have captivated audiences worldwide for 25 years. Herdman portrayed Gregory Goyle, a Slytherin student who, alongside Draco Malfoy and Vincent Crabbe, antagonised Harry Potter and his friends. Bulgarian actor Yanevski played Viktor Krum.
Organisers expect more than 3,000 visitors. The convention will feature science fiction associations, lectures, gaming sessions, tournaments, board game demonstrations, a book fair, a sales exhibition and a cosplay competition.
SFeraKon is supported by the City of Zagreb and the Ministry of Culture.