Michelle Williams at the Oz premiere

Michelle Williams used 'Oz the Great and Powerful' as a ''love letter'' for her daughter.

The 32-year-old actress plays Glinda the Good Witch in Sam Raimi's upcoming Disney film and chose to star in the feature as she felt it was ''made'' for seven-year-old Matilda - whose father is the late actor Heath Ledger, who tragically died from an accidental overdose in 2008.

She explained: ''['Oz the Great and Powerful'] was a love letter for my daughter ... It was made for her, that was the spirit in my heart when I made it.

''She would visit me at work. She got to go through the hair, make-up and wardrobe, visited the animals and sat next to Sam, holding his hand.''

Michelle has previously been type-cast as sad and troubled characters - such as in 2010's 'Blue Valentine' and her Oscar-nominated portrayal of Marilyn Monroe in 'My Week With Marilyn' - and the blonde beauty was happy to prepare for a role which shows the happier side of her personality.

She added in an interview with Look magazine: ''['Oz'] was exactly the kind of film I wanted after so many sad roles. It was like an antidote. I always like to spend some time in the months ahead kind of setting a mood, so I watched movies like 'Fantasia' or 'The Princess Bride'.

''But I think that was because I stopped going to school when I was 15, I always have some kind of nervousness of not being prepared enough.''

© Bang Showbiz