Iconic 1980s Hollywood star is unrecognizable in horror film BTS snaps for Halloween. Who is she?

A Hollywood icon of the 1980s and 1990s was completely unrecognizable in an Instagram album she posted for Halloween.

At the height of her fame, she was widely recognized for her stirring performances - and her fearless attitude to being naked onscreen.

This year, she broke boundaries again by appearing in a full-frontal nude scene aged 61 in a horror movie that became a sensation at the Cannes Film Festival.

In honor of the spooky season, she fired up her Instagram page this Thursday to pose a series of behind-the-scenes snap from that project.

Her unmistakable features and her still youthful figure were totally obscured by an old-age prosthetic, as well as occasionally fake blood.

Demi Moore posted the pictures, which were taken on the set of her buzzy new horror movie The Substance starring her and Margaret Qualley. 

'Been holding onto these gems from @trythesubstance and today feels like an appropriate day to share them. Happy Halloween from Elisabeth Sparkle,' wrote Demi in the caption, name-checking her character in the movie.

The ex-wife of Bruce Willis also noted that The Substance had just become available on the streaming platform MUBI that day. 

Demi leads the cast of The Substance as Elizabeth Sparkle, a movie star whose career is on the decline because of her advancing age.

Elizabeth finds out about a fluid called The Substance, which she can inject to create a younger version of herself who can act in her place.

Sue, played by Margaret, emerges as the new youthful version of Elizabeth, who has to move her mind back and forth between the young and old bodies every week.

However, the process of keeping the Sue body in operation causes Elizabeth's original body to grow dramatically older extremely fast. 

Since opening in theaters last month, The Substance has earned over $41 million at the global box office, more than double its budget of $17.5 million.

It was greeted by a similarly glowing response from the critics, to the point it now enjoys a sterling 91% rating on Rotten Tomatoes. 

Demi has been known for flashing the flesh since her 'Brat Pack' days, when her sex scenes with Rob Lowe in the 1986 film About Last Night... drove audiences wild.

She has disrobed in movies ranging from the 1993 erotic drama Indecent Proposal to the 1995 historical romance The Scarlet Letter to the 1996 comedy Striptease.

In 1991, she broke ground and ignited a controversy by posing naked on the cover of Vanity Fair while seven months pregnant by her then-husband Bruce Willis.