Branagh is yet to announce who will play the lead role in Thor
Marvel entertainment is delaying the release dates of two forthcoming comic book movies, Thor and The Avengers.
Thor, which will be directed by Kenneth Branagh, will be released a year later than originally planned, in June 2011.
The Avengers - a multi-character movie featuring the likes of Iron Man, The Hulk and Captain America - will be released in May 2012.
Marvel say the decision has been made to avoid clashing with other superhero films due out at the same time.
No less than three big screen adaptations are expected over the next three years.
The First Avenger: Captain America is expected out on 22 July 2011, though no casting for lead role has been announced yet.
Casting is coming together for Iron Man 2 with Mickey Rourke and Scarlett Johansson recently signing on for the project, which will start shooting this year.
The fourth instalment of Spider-Man has also been announced, and another Batman movie looks likely after the huge box office success of The Dark Knight.
In addtion, Samuel L Jackson recently signed a nine-picture deal to play superhero Nick Fury.