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"Private Practice" actress Agnes Bruckner has been transformed from brunette tomboy to the blonde bombshell Anna Nicole Smith for Lifetime's new biopic.

" Entertainment Tonight" got a first look at Bruckner as the tragic Playboy model on the set of the upcoming made-for-TV movie "The Anna Nicole Story."

"The transformation has been amazing," Bruckner told "ET." "I came into this a brunette - a total tomboy."

Indeed, the resemblance - created in part with hair, makeup and prosthetics, according to Bruckner - is uncanny.

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Beyond looks, Bruckner, 27, dived into the role after doing hours of research.

"I watched 'ET' stories, YouTube clips. So much of her life was on camera," she said.

"It's just such a fascinating story to me. There were so many different layers to her, and she was so iconic and so larger-than-life. It was just something that I was like, 'This is gonna be really scary but it's gonna be really awesome at the same time.'"

Bruckner, who made her feature film debut as a high school student having an affair with her teacher in 2002's "Blue Car," was featured in "The Glass House" and "Murder By Numbers," costarring Sandra Bullock. She has also appeared in a number of television shows, and last year starred in another Lifetime movie, "The Craigslist Killer," as the killer's girlfriend Megan McAllister.

"The Anna Nicole Story" will chronicle Smith's evolution from Vicky Lynn Hogan, a pretty but plain girl growing up in a small Texas town, to Anna Nicole Smith, the voluptuous Playboy pin-up and model.

"She had so many ups and downs - weight gain and then lost it - she was messy and crazy and then she was really put-together at times," said Bruckner.

Bruckner's co-star Adam Goldberg, who plays Smith's lawyer/boyfriend Howard K. Stern, gives Bruckner kudos for her portrayal of Smith, which he says could easily have fallen into an impression of the late model.

"She's not doing an impression of [Anna Nicole]," Goldberg told "ET." "I think it's a very difficult role to play because there is just so much tape on this woman that's it's very easy to just do an impression. … You have to find something in it that is honest for yourself and I think that's what Agnes is doing."

Goldberg has posted pictures of Bruckner as Smith on his Tumblr.

The film will also feature Hollywood legend Martin Landau as J. Howard Marshall, the Texas oil billionaire who married Smith despite their 63-year age difference.

"We think of J. Howard as an old geezer who picked her up in a strip bar," the actor told "ET." But Landau said he was a magna cum laude graduate from Yale who became one of the world's most foremost lawyers advising FDR's cabinet during World War II before moving to Texas to make his fortune.

Smith, who went on to star in her own reality show, died in 2007 at the age of 39 from a drug overdose. After a dramatic paternity battle following her death, Larry Birkhead was awarded custody of his and Smith's daughter, Dannielynn, 5.

Stern and Smith's psychiatrist were later convicted of drug conspiracy for obtaining prescription drugs for Smith. The convictions were overturned, then an appellate court ruled they should be reinstated.