But in the actress' personal life, she had another important role: bride.
Hathaway was planning her wedding while at work on the project. How, then, to have the perfect ceremony when her day job required she trade her long brown locks for a cringe-worthy buzz cut?
"When I eventually looked in the mirror I just thought I looked like my gay brother," Hathaway told an audience in New York on Friday at the first screening of director Tom Hooper's take on the beloved musical.
She also dropped 25 pounds (though we've never heard a bride complain about weight loss) and worked for months with a vocal coach to meet Hooper's demand for live singing (as opposed to dubbing over filmed performances with studio-perfected tracks).
Hathaway called the feat a "mixed bag," adding it was “wonderful to have the freedom to turn your brain off and just live it" but she certainly felt the pressure.
As for that hair -- she compromised, donning a headpiece in addition to a veil when she tied the knot with actor Adam Schulman in October.
A small price to pay, if you ask us. Her Fantine seemed to bowl over the New York industry crowd, with many an outlet tipping her for a best supporting actress Academy Award nomination. What's a few inches of hair for Oscar gold?