And weirdly, Katie reckons changing hair colour actually changed her into a different person altogether...
"It was so odd being blonde," says Katie. "I'd go into work as Katie, but no sooner had I put on the blonde wig, people treated me differently and I acted differently. Somehow It gave me an entirely different walk. I had a rushed sort of totter as a blonde. It was bizarre!"
Katie plays Victorian era socialite Lucy Westenra, who's the best friend of Mina Murray (Arrow's Jessica De Gouw) - the woman Dracula becomes obsessed with over the 10-part series.
"Lucy is a very social girl," explains Katie. "She's high class and intelligent and used to being the focus of every room."
Seeing lead actor Jonathan Rhys Meyers as Dracula didn't cause any fang-jealousy amongst the cast apparently.
"They are not comfortable to wear I can tell you!" laughs Katie, who also starred alongside Jonathan in BBC2 series The Tudors. "And Jonny sounded like Daffy Duck with them on!
"Seriously, although the show is called Dracula, it's not really about vampires as such, it's about the relationships between all the characters, and the fact that one of them is a semi-supernatural being is actually just a small part of it. The story is about revenge, love and conflict. What's great about this show is you can root for all the characters, even though all have darker elements."
Dracula premieres on Sky Living, on October 31 at 9pm.
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