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ABC News' Linsey Davis and Natasha Singh report:

Nazanin Boniadi had been a relative unknown, but that all changed with Vanity Fair magazine's explosive report that the actress had a secret relationship with Tom Cruise shortly before he began dating Katie Holmes.

Vanity Fair's article alleges that Boniadi was selected by the Church of Scientology as a candidate to be Tom Cruise's real-life girlfriend. The church has denied the allegations.

So, just who is the woman at the center of the controversy?

Before she discovered her love of acting, Boniadi received her bachelor's degree with honors in biological sciences from the University of California-Irvine, and even won an award for her cancer-treatment research.

Born in Iran just after the revolution there and raised in London, Boniadi, 32, is an official spokeswoman for Amnesty International, which works to protect human rights around the world.

While she has now received attention for her alleged love interest off-screen, on-screen she played the girlfriend of Barney Stinson, the womanizing character played by Neil Patrick Harris on the popular CBS sitcom "How I Met Your Mother."

Boniadi also had supporting roles in box office hits "Iron Man" and "The Next Three Days."

RELATED: Paul Haggis Supports Vanity Fair Story on Tom Cruise Girlfriend Audition

The starlet has even played opposite Hollywood A-lister George Clooney in a European commercial for Nespresso coffee machines, and has become a regular on the soap opera "General Hospital."

Vanity Fair wrote that the church auditioned devout Scientologist actresses as potential real-life love interests for Cruise, and they chose Boniadi as a candidate. She allegedly went through a month-long vetting process before she met Cruise for the first time in November 2004.

Maureen Orth, who wrote the article, told "Good Morning America" Wednesday that Boniadi and Cruise eventually became inseparable.

Their relationship allegedly ended three months later, with claims that Boniadi wasn't as publicly affectionate with Cruise as the A-list actor wanted, and that he believed she was disrespectful to the leader of the Church of Scientology, Orth said.

Boniadi, the magazine writes, was then reportedly sent to a Scientology center where she broke down and revealed her relationship with Cruise to a friend, which supposedly violated her confidentiality agreement. As punishment, Vanity Fair says, her chores included "scrubbing toilets with a toothbrush, cleaning tiles with acid and digging ditches in the middle of the night."

Boniadi is no longer involved with Scientology. She is not speaking publicly about the allegations, and didn't respond to ABC News for a comment.

Reacting to the allegations in the article, a representative for Cruise told ABC News in a statement Monday: "Lies in a different font are still lies - designed to sell magazines."

But Oscar-winning director and former Scientologist Paul Haggis has supported Vanity Fair's story.

In an email to ShowBiz411.com, the "Crash" director wrote that "Naz was embarrassed by her unwitting involvement in this incident and never wanted it to come out, so I kept silent. I was deeply disturbed by how the highest ranking members of a church could so easily justify using one of their members; how they so callously punished her and then so effectively silenced her when it was done."

The church has described Haggis and other sources Orth interviewed for her article as liars and "apostates," and characterized the entire article as "hogwash."

To see Scientology's response to the Vanity Fair article, click HERE.

Cruise went on to marry Holmes. He and the actress separated earlier this year after nearly six years of marriage. Their divorce was finalized in August.

ABC News' Kevin Dolak contributed to this report.