Alexander Skarsgard bases his ‘True Blood’ character on a lion

The Swedish actor – who plays vampire Eric Northman in the hit US drama – studied the jungle creature intently in order to figure out how best to portray someone with hidden menace behind their charm.

He said: “I wanted to underplay it a bit and make it real. At the same time, I try to find that animalistic quality, and the element of danger.

“I was fascinated by the male lion on a documentary, the way he moved, the confidence. When he just sat down and looked straight at the cameraman, he did absolutely nothing, but for a second you didn't know whether he was going to yawn and fall asleep or pounce.

“I thought it would be interesting to try to find that. You don't show your teeth, you don't say anything, you don't show it. It's the not knowing that's interesting. Anything could happen.”

Alexander loves working on the show, but admits he is unsure how long he can continue with the role – unless he has cosmetic surgery to appear younger.

He said: “Well I don't know how many years. I'm not supposed to age, so we might have a bit of a problem when I'm 55 and still playing Eric, it might get kind of pathetic.

“We still have a couple of years. I do live in Los Angeles, so I can cheat with Botox and plastic surgery. That was a joke, by the way.”