From saints to sinners, stars around the world dressed in religious garb for the Catholic-themed Met Gala at the Metropolitan Museum of Art's Costume Institute ball last night.

Rihanna, who co-chaired the event with Vogue editor Anna Wintour, Amal Clooney and Donatella Versace, attracted the most controversy dressed as the pope for the annual celebrity event.

The Barbadian superstar faced some criticism for her outfit under the 2018 theme of: 'Heavenly Bodies: Fashion and the Catholic Imagination.'

But despite the backlash, the 30-year-old said it would have been a 'sin' not to wear the Maison Margiela designed costume complete with mitre and cropped cope.

'It feels expensive! It would be a sin not to wear it!' she told Vogue.

The invitation-only Met Gala is a fundraising benefit for the Metropolitan Museum of Art, and also marks the opening of the Costume Institute's annual fashion exhibition.

The 2018 exhibit shows how Catholicism has influenced fashion and designers through the decades and features more than 50 vestments and other religious items on loan direct from the Vatican.

Madonna, a key religious provocateur early in her pop career, turned demure in a black, long-sleeved gown, with a huge gold crown, and a full face veil.

Kim Kardashian, appearing without husband Kanye West, kept it simple in a curve-hugging, gold metallic floor length dress with plunging neckline by Versace.