She's one of the biggest stars in music with tens of millions of fans.
But it's one fan in particular that's causing Shania Twain a world of trouble.
It was at an awards ceremony in Canada earlier this year that 50-year-old Giovanni Palumbo, a surgeon, was arrested.
Authorities say he showed up at the venue despite being ordered to stay away from the superstar after sending her hundreds of letters.
"I know you're playing hard to get, no scratch that, impossible to get, and that's because you know you are perfect and so am I," said one letter from stalker Palumbo.
"I can be free any time. I will do anything and everything, for I truly need you," said a later letter.
Aside from the creepiness of the letters, there was another problem. Dr. Palumbo was not free.
At the time, he was married to Christel Palumbo. She claims her husband was so obsessed with Twain that he wanted to turn her into the object of his obsession.
"He would show me the way she dresses, and say, 'Look how feminine she is. Comb your hair like her, you should get dressed like her, and be skinny like her.' We had a wedding picture, and he had taken away that picture, and put a picture of Shania Twain," said Christel.
Christel was married to Palumbo for 16 years, and they divorced in 2010.
The Twain issue was just too much to take.
"There was almost like a shrine to her, with pictures of her on the dresser, and candles," said Christel.
Palumbo was convicted of assaulting his wife in 2007. She says even that incident involved Twain.
"He tried to make me angry by putting her music really loud, and saying how great she is and how much better, and I got really upset, and he tried to strangle me," said Christel.
Twain has been testifying via closed-circuit TV from an undisclosed location in Europe.
Twain said, "I still have fear and anxiety of being contacted in the future, and I do want it to stop."
Palumbo's ex-wife thinks Twain still doesn't know the extent of his obsession.
"I didn't even understand at that point how deep it was," said Christel.