Her last appearance in the Marvel Cinematic Universe (MCU) was in 2013's Thor: The Dark World.

Natalie Portman made a surprise return to the fold when she appeared at the premiere for Avengers: Endgame in Los Angeles on Monday.

The 37-year-old Oscar winner's appearance raised the specter of a return to the massively popular superhero franchise.

She's back! Natalie Portman, 37, made a surprise return to the fold when she appeared at the premiere for Avengers: Endgame in Los Angeles on Monday

The 5ft3in Black Swan star arrived in an understated and tasteful black dress.

The skirt was covered in glittering black sequins, and the lower half featured an intricate nature scene that appeared to feature flamingos and tropical plants.

Natalie's sleeveless sweater top showed off her toned arms, just as the slit in her skirt put her slender legs on display.

She completely the look with a pair of black open-toe heels, and had her brunette locks parted down the middle and tied back in a low-slung bun.

Stunning: The 5ft3in Black Swan star arrived in an understated dress covered in glittering black sequins, with the lower half featuring an intricate nature scene that appeared to show flamingos and tropical plants

Gorgeous gams: Natalie's sleeveless sweater top showed off her toned arms, just as the slit in her skirt put her slender legs on display

Natalie first starred opposite Thor's Chris Hemsworth in his eponymous 2011 film as Dr. Jane Foster, an astrophysicist who stumbled upon the Asgardian god after he was exiled to Earth.

The two characters struck up a romance, and Natalie returned for the 2013 sequel, but her participation in the Marvel universe ended there.

She was written out of future Avengers films and 2017's Thor: Ragnarok, like many of the other female love interests in the MCU.

Ancient history: Natalie first starred opposite Thor's Chris Hemsworth in his eponymous 2011 film as Dr. Jane Foster, an astrophysicist who stumbled upon the Asgardian god after he was exiled to Earth

Marvel Studios President Kevin Feige addressed her absence from subsequent Marvel films, essentially saying the characters broke up.

'We wanted Thor to encounter somebody that was near his equal and that his relationship with Jane may have evolved in unexpected ways in between The Dark World and Ragnarok and we wanted to pit him against a character who was much more his equal and in many ways his superior,' he said, speaking to Entertainment Weekly.

That doesn't quite address why Marvel has most of the non-superhero women featured in the early Marvel Studios releases.

Natalie's appearance at the LA premiere, after a five-year absence, raised the specter that she might have some small role in Endgame, or might return in a future release.

Back at it? Her character was written out of future Thor installments, though her surprise appearance raised the possibility of a small role in Endgame or a future return to the franchise

Old flame: Chris Hemsworth starred opposite Natalie in the first two Thor films, though she was absent from Thor: Ragnarok and the Avengers films

Recently, the Annihilation star has been focusing on her activism.

She appeared at a US Women's Team soccer game earlier this month with Jessica Chastain, Jennifer Garner, Eva Longoria and other celebrities to support the team in it's lawsuit for equal compensation with the US Men's Team.

She's slated to appear in Lucy In The Sky later this year, a drama loosely based on American astronaut Lisa Nowak, who was charged with kidnapping, burglary and battery after she pursued a former lover and fellow astronaut.