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On the Croisette, 61-year-old Moore will be making her unexpected return in slasher-horror "The Substance", competing for the festival's top prize, the Palme d'Or.
It has been a long time since Moore came anywhere near a Cannes red carpet, having appeared mostly in small TV roles and forgettable films since the early 2000s.
In her heyday, Moore was a global star after the weepie "Ghost" co-starring the late Patrick Swayze as a murdered businessman who watches over his grieving ceramicist girlfriend from beyond the grave and famously helps her mould clay in a steamy supernatural scene.
Her baggy, androgynous look in that movie -- the dungarees and boyish crop -- helped define 1990s style, and she had other era-defining hits with steamy dramas "Indecent Proposal" and "Disclosure".
An Annie Leibovitz photoshoot -- showing off her pregnant belly on the cover of Vanity Fair in 1991 -- was a stunning move at the time since copied by Beyonce, Rihanna and others.
She proved her acting chops in meatier 1990s movies such as the blockbuster courtroom drama "A Few Good Men" opposite Tom Cruise and Jack Nicholson.
But since the turn of the century, Moore, who has a life-long passion for collecting dolls and bought an entire house to store her 2,000-strong collection, was in the headlines more for her tumultuous love life than her acting.
She formed two Hollywood power couples, first in the 1980s with "Die Hard" star Bruce Willis, the father of her three daughters, and then with Ashton Kutcher, the latter union ending acrimoniously in 2013.
The soft-spoken 69-year-old is back in Cannes in his favourite genre, the Western, with the epic "Horizon: An American Saga".
Fans are hoping his fourth feature as director, which is out of competition at Cannes -- will mark a return to form after a series of expensive duds in the 1990s trashed his Oscar-gilded career.
His directorial debut "Dances With Wolves", despite being a three-hour Western, was a global hit and in 1991 won the double Oscar whammy of best picture and director.
As an actor he captured hearts in smash hits "Robin Hood: Prince of Thieves" (1991) and as Whitney Houston's protector in "The Bodyguard" (1992).
Teaming up with big-gun directors also proved a winning formula, from Oliver Stone's "JFK" (1991) to Clint Eastwood's "A Perfect World" (1993).
But then a string of ultra-expensive and hubristic flops, especially "Waterworld" (1995) and "The Postman" (1997) made him into something of a laughing stock.
Gere was the world's sexiest man according to People Magazine in 1999 when he was 50.
By then he had charmed audiences with his quiet seduction in "An Officer and a Gentleman" (1982) and, of course, "Pretty Woman" opposite Julia Roberts.
He and supermodel Cindy Crawford were also the ultimate It-couple.
But progressively he gave up glamour for meditation.
Gere had been a Buddhist since he was 25, and increasingly used his fame to speak out, in particular against China's control of Tibet.
He developed a close friendship with the Dalai Lama and gave a fiery speech against China at the 1993 Oscars getting him barred from the ceremony for life.
It also cost him movie roles in the 2000s as Hollywood sought to tap the vast Chinese market.
For his Cannes comeback, the 74-year-old has reunited with Paul Schrader, who directed him in dark cult favourite "American Gigolo" (1980), for "Oh, Canada", playing a Vietnam War draft-evader haunted by his past.
