Ryan Kwanten is to star as infamous serial killer Charles Manson in a new film about the Manson family, it's been reported.

The True Blood star - known for playing lothario vampire Jason Stackhouse in the hit show - has been cast in The Family, written and directed by The Machinist scriptwriter Scott Kosar.

Scott told movie blog Shock Till You Drop: "The movie won't focus on the Manson murders, nor is it a Manson biopic, it's a family biopic.

"A movie about a surrogate family of wayward teenagers who, through extraordinary circumstances, came together and were transformed into the most notorious American family of the 20th century. Hence the title."

Meanwhile, Ryan has joked he is being haunted by panthers.

He had to film with real panthers for True Blood and he was told he also had to film with a panther for new Australian western Red Hill.

But when producers learnt that the panther had turned on its owner in a deadly attack, Ryan was spared the risky scenario, and had to rely on old-school acting instead.

Ryan said writer/director Patrick Hughes pretended to be the panther off camera. He said: "It was my finest bit of acting to keep a straight face and try to stay in it while my director was licking his paws and carrying on." Another panther was filmed for scenes added in later.

"You're definitely on your toes when working with the big cats," he said.