Fantasy and science fiction fans might be forgiven for geeking out at this year's San Diego Comic-Con, going by the reveals over the weekend.

Fans of George R. R. Martin's Game of Thrones cheered at seeing the new cast members unveiled for season five of the popular HBO fantasy TV series.

The new additions were announced via a two-minute video, in which the actors revealed the characters they would be playing.

Many of the new cast will play characters primarily based in the desert kingdom of Dorne.

Among the new faces joining the show is Alexander Siddig, who will be playing Doran Martell, the stoic ruler of Dorne and older brother of the gruesomely slain Prince Oberyn.

Siddig starred in thriller drama 24 and Star Trek: Deep Space Nine.

Oscar-nominated New Zealand actress Keisha Castle-Hughes will play the fiery Obara Sand, one of Prince Oberyn's illegitimate daughters who is seeking revenge for her father's murder at the hands of the Mountain in season four.

Castle-Hughes is best known for her role in 2002's critically-acclaimed Whale Rider and her turn in Star Wars Episode III: Revenge of the Sith.

The highest-profile name joining season five is Jonathan Pryce, who will star as the High Sparrow, a religious figure who could be making waves in King's Landing. Pryce has had a successful career spanning four decades and played the villainous media mogul Elliot Carver in James Bond film Tomorrow Never Dies.

Meanwhile, DC Comics said that four of its comic titles will make their appearance on the small screen later this year.

Gotham, based on the Batman comic, premieres on Sept 22, The Flash debuts Oct 7, Arrow returns on Oct 8 and supernatural drama Constantine debuts on Oct 24.