Last year's theme Heavenly Bodies: Fashion and the Catholic Imagination, evoked religious art, while 2017's gala made allusions to technology with its Manus x Machina theme.
Spanning the understated, the extravagant and outright audacious, here's a selection of red carpet looks from the annual fundraiser.
Priyanka Chopra walked the Met Gala pink carpet with husband Nick Jonas, who was also included in the meme fest.
The theme was created by the Costume Institute's Andrew Bolton, who asked attendees to draw inspiration from Susan Sontag's 1964 essay Notes on "Camp".More news: Woman pulls alligator from her pants during traffic stop
Gaga wasn't the only one to shock attendees at the gala. But does Leto's "decapitated" likeness bring to mind Rammstein singer Till Lindemann's severed head, shown onscreen in the recent "Deutschland" music video (NSFW) from the German industrial outfit?
Katy Perry arrived at the Met Gala dressed as a chandelier.
For her final look, Gaga ditched the dresses, opting to strip down into a glittering brassier and underwear set with fishnets and huge platform shoes.
Gucci creative director Alessandro Michele and singer-songwriter Harry Styles arrive for the Met Gala at the Metropolitan Museum of Art on May 6, 2019.
Zendaya looked wonderful in a custom Tommy Hilfiger look, and lit up light magic on the red carpet. She dropped one of her see-through slippers on the way up the long staircase at the Metropolitan Museum of Art for the cocktail hour.