She was matchy-matchy with her Girls co-star Allison Williams, for colour anyway. Dunham's gown was smooth while Williams' Armani Prive was full-on beaded ruffles. Helen Mirren also wore red, a fine silk Dolce & Gabbana with stone detail.
Williams wanted a "real girl" dress after her turn as Peter Pan.
Also extending the red trend last year was Viola Davis, the How to Get Away with Murder star who stunned in a silk Donna Karan Atelier strapless with pleats and mirrored sequins on the corset.
Presenter Jennifer Lopez went for Old Hollywood in a silver Zuhair Murad art deco inspired caftan with a full cape, high slit and plenty of decolletage.
"I love him. He's one of my favorite designers," she said.
Emily Blunt wore a full white couture gown by Michael Kors. The colour made her nervous, she said, considering an early rain that cleared by carpet time, but "mainly because I'm clumsy and I have a baby that can spill stuff on it."
She added to E!: "It's a little soggy at the bottom."
Julianne Moore wore a silvery embellished custom Givenchy Haute Couture by Riccardo Tisci that went from embellished silver metallic sequins to black ostrich feathers at the bottom as she chatted about playing dress up.
"I think the fashion game has changed considerably in the last 10 years or so. We have access to things that we really didn't have access to before," she said. "It's really fun."
• Check our our best and worst dressed on Life & Style tomorrow
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