Gillian Anderson and David Duchovny most recently reunited for a two-season revival of the beloved sci-fi series, which ran from 2016 to 2018

Gillian Anderson and David Duchovny are together again.

On Sunday, the duo had an X-Files reunion as Anderson, 52, shared a selfie with her longtime pal, 60, and her new dog Stella on Instagram. "Stella made a new friend today," she wrote in the caption of the photo.

Anderson and Duchovny starred as FBI special agents Dana Scully and Fox Mulder, respectively, in the beloved sci-fi series, which premiered in 1993 on Fox, before bowing out after nine seasons in 2002.

Both stars also appeared in the feature film spinoffs in 1998 and 2008, before returning for a two-season revival, which ran on Fox from 2016 to 2018.

Duchovny recently spoke about the show and how he almost turned down the role, telling on Rob Lowe on his podcast Literally! With Rob Lowe: "X-Files, this is about extraterrestrials. How long can it go? It's a good pilot but you're either going to see the aliens or [not]. I wasn't interested in conspiracy theories, and I was perfectly willing to just say, 'I'm going to have to pass on that pilot, because I said I'd do this other project.' It's scary to think back on, if you didn't open this door, or you took that left instead of that right. It's like, none of it had to happen. You talk about actors being dumb… well, that was me."

Their latest reunion comes after Fox announced in August that an animated spinoff entitled The X-Files: Albuquerque is in the works.

Although X-Files creator Chris Carter signed on as executive producer, Anderson and Duchovny were not involved at the time, according to Variety.

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Credit: Fox/Everett

Anderson confirmed in 2018 that she was done playing Scully, after her character was unceremoniously written off the final season of the revival. "It's time for me to hang up Scully's hat. It just is," she said at the time. "I'm finished and that's the end of that."

She previously called out the all-male writing team of season 11. "I too look forward to the day when the numbers are different," she wrote on Twitter, also pointing out that only two of the 207 episodes were directed by women.

The Crown actress most recently won a Screen Actors Guild Award for her portrayal of Margaret Thatcher in the Netflix drama. (She also won a Golden Globe for her performance.)

Margaret Thatcher (GILLIAN ANDERSON) The Crown
Gillian Anderson as Margaret Thatcher
| Credit: Sophie Mutevelian/Netflix

Anderson thanked her ex and The Crown creator Peter Morgan in her SAG Awards acceptance speech. "And last, but never least, Peter Morgan for creating so many multidimensional roles for all us actors to sink our teeth into and win awards for," she said. "Thank you, thank you, thank you."

Anderson and Morgan amicably split in December, after four years together. A source told PEOPLE at the time that the pair has "highly-demanding schedules."