(L-R) American actresses Meghann Fahy and Haley Lu Richardson attend PEOPLE's post Screen Actors Guild Awards Gala at Fairmont Century Plaza on February 26, 2023 in Los Angeles, California. (Photo by Kevin Mazur/Getty Images)

“You” star, American actress Victoria Pedretti locks lips with American actor Fred Hechinger in New York City on February 26, 2024. (Photo by The Image Direct)

The photo project was done for the organization Fishlove and included some other U.K.-based celebrities posing in the buff with critters ranging from bass fish to sharks. Its goal is to raise awareness of how overfishing is destroying the oceans. The release of Gillian's nearly nude pic, which was snapped by French portrait photographer Denis Rouvre, is timed with a European Parliament vote on banning destructive forms of deep-sea fishing in the Northeast Atlantic. The Fishlove organization is trying to rally voters to sign a petition ending deep-sea trawling – which, according to scientists, is negatively impacting the fish population and their habits – and Gillian solicited signatures in a Twitter post. Photo: “Fish Love” Project by Photographer Denis Rouvre. Gillian Anderson. (Photo by Denis Rouvre)

Kaia Gerber attends the LOVE Magazine LFW Party, celebrating issue 23 at The Standard, London on February 17, 2020 in London, England. LOVE magazine is welcoming Ben Cobb as Editor-In-Chief Men's, Graham Rounthwaite as Creative Director, and Oliver Volquardsen as Fashion Director. (Photo by David M. Benett/Dave Benett/Getty Images for LOVE Magazine)

Best portfolio winner. Roseate Spoonbill, Platalea ajaja, by Petr Bambousek, Czech Republic. (Photo by Petr Bambousek/2018 Bird Photographer of the Year)

English and Albanian singer-songwriter Dua Lipa in the second decade of December 2022 channels Catwoman in leather. (Photo by dualipa/Instagram)

American singer-songwriter Camila Cabello shows off a unique design from Iris van Herpen in Paris, France early July 2023. (Photo by camila_cabello/Instagram)