The image features her with Peter Dinklage and Nikolaj Coster-Waldau -- the actors who play her on-screen siblings Tyrion and Jamie -- all dressed in their medieval-style attire from the series.
Headey is seen licking the face of Dinklage as Coster-Waldau grins wildly.
"Now this is more like it. Congratulations to my brothers (literally) from other mothers. I'm a lucky lucky sista to these Mistas. Love you PD and @nikolajwilliamcw," Headey captioned the undated snapshot.
"Game of Thrones," which goes into its eighth and final season in 2019, was nominated Thursday for more Emmys than any another series.
It is up for the top title of Best Drama, and Headey, Dinklage and Coster-Waldau received nods for Best Supporting Actress in a Drama and Best Supporting Actor respectively.
A prequel series called "The Long Night" is to begin shooting in Belfast in October.
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