Fans of The X-Files rejoiced when its two stars, Gillian Anderson and David Duchovny, reunited in an Instagram photo.

In a post on Sunday (April 18), Anderson put up two photos of them with her pup Stella, writing: "Stella made a new friend today."

Anderson, 52, and Duchovny, 60, starred as FBI special agents Dana Scully and Fox Mulder in the cult classic science-fiction series.

Fans who adore the iconic couple of Mulder and Scully gushed over the photo, with one commenting: "Can't you just marry already?"

The X-Files ran for nine seasons from 1993 to 2002, and Mulder and Scully also made big-screen appearances in 1998 and 2008.

The two stars, who have remained pals over the decades, returned for a two-season revival from 2016 to 2018, after which Anderson declared she was done.

"It's time for me to hang up Scully's hat. It just is," she said in January 2018 to The Hollywood Reporter. "I'm finished and that's the end of that."

Meanwhile, Duchovny was open to playing Mulder again, saying he was "good either way".

An animated spin-off titled The X-Files: Albuquerque was announced in August last year, with original series creator Chris Carter as executive producer. Neither of the stars is involved in it.