The actress is seen striking a bizarre pose with her arm up behind her head looking more like she's in a fashion shoot than a sci-fi film.
In a video on her personal TikTok, Gillan, who is nearing a decade as the daughter of Thanos in the Marvel films, said she took “full responsibility” for the decision.
She said: “Okay, can anybody tell me what I was thinking when I decided to pose like this on an international, worldwide poster that will remain forevermore?
“I remember doing this pose and thinking, ‘I think I look pretty cool here.’ (laughs) So I take full responsibility for this choice, but oh my God, what am I leaning against? What is my elbow doing?"
The Nebula actress remarked that “Maybe I should double down and make this pose a thing," adding: “I stared at it for so long, I was like, ‘Oh maybe, I’m reaching for a weapon to take out and fight someone.’
“And then I remembered that I’m not wearing a holster or anything that would carry a weapon, so it’s not that either.
“You’ll be seeing that pose again somewhere where you’ll least expect it.”
Fans appreciated the star not taking herself seriously and flooded her comment section with praise for her response, some even insisting they loved the image.
The sentiments were a far cry from before she replied to the backlash when trolls slammed the poster and even made sexist comments about her not being “feminine enough" to pull off the look.
The awkward image has since generated a series of humorous memes online.
Guardian of the Galaxy Vol. 3 is scheduled to be released in theaters on May 5, 2023