"Thank you to all of my fans and supporters for making this already unforgettable weekend so much more beautiful," the actress wrote alongside a selfie with several flower bouquets, seemingly snapped backstage at the Massachusetts theater festival.
"The flowers won't last forever, but the memories of all the love and support I received through this, will," she concluded the caption.
Heard's post was met with even more support, including from fellow actresses Julia Fox and Iris Apatow, who commented "QUEEN" and "Angel," respectively.
Spirit of the People is a "haunting bilingual epic where Zapotec warriors, expats, mezcaleros, and sex tourists collide in Oaxaca where the world could be ending as the waves continue to pound on the shore," according to an Instagram post shared by the theater festival on July 9.
Acclaimed playwright Harris -- best known for his 2018 Tony Award-nominated play Slave Play and co-writing 2020's Zola -- previously told Variety that with the show, he "wanted to challenge myself" by writing a play that is "half in Spanish." (Star Heard has been living in Madrid in the years since her legal battles with ex-husband Johnny Depp concluded in 2022.)
Alongside Heard, Spirit of the People also featured actors Ato Blankson-Wood, Zachary Booth, James Cusati-Moyer, Amandla Jahava, Emma Ramos, Julian Sanchez and Tonatiuh, according to the theatre festival's official website.
The world premiere production marked Heard's first acting role since 2023, when she starred in the movie In the Fire. The same year, she also made an appearance in Aquaman and the Lost Kingdom, reprising her role as the character Mera opposite Jason Momoa as the titular hero.
Heard documented her return to acting throughout the process, first with a selfie featuring Harris, alongside which she declared she is "In my theatre era x."
She later followed up the selfie with a photo of herself seemingly rehearsing for the play, sitting on a stage alongside a script and highlighter. "Work in progress," the Aquaman actress wrote alongside the post, in which she tagged the Williamstown Theatre Festival.
Before the play's final weekend, Heard also marked the beginning of the end of the play's debut run with a backstage selfie.
"Lucky to be stealing one final breath before this weekend's final performances," she wrote in the caption. "Last chance to see Spirit of the People at @wtfestival !"