King Harald (wielding battleaxe and clad in red) - taken from 'The life of King Edward the Confessor'.
According to Hollywood industry website Deadline, Warner Brothers has signed a "blind script deal" with screenwriter Mark L Smith, who is developing the script as a vehicle for DiCaprio.
DiCaprio, a history buff, has long been interested in headlining a Viking movie, and was once slated to star in a Mel Gibson Viking epic that was eventually never made.
The Great Gatsby star will co-produce the film alongside Jennifer Davisson Killoran, his partner in production company Appian Way.
Harald Hardrada ruled Norway from 1046 until 1066, when he was killed at the Battle of Stamford Bridge, bringing the last Viking invasion of Great Britain to an end.