The online trailer for the ninth film in the original Star Wars saga has attracted more than 16 million views in 24 hours.

Key points: Star Wars: Episode IX will be the final film in the series, which first started in 1977

Star Wars: Episode IX will be the final film in the series, which first started in 1977 The film will feature evil emperor Palpatine, who appeared to die in 1983's Return of the Jedi film

The film will feature evil emperor Palpatine, who appeared to die in 1983's Return of the Jedi film Director JJ Abrams used footage of the late Carrie Fisher from a previous film to include her in the latest instalment

Disney showed fans attending the Star Wars Celebration convention in Chicago the first footage from the movie, which will be released in theatres in December and will conclude the story that began in 1977.

The film will be called The Rise of Skywalker, and will feature the return of the evil emperor Palpatine to threaten the young heroine Rey and the Resistance.

A villainous cackle was heard at the end of the trailer, and the actor who played Palpatine in previous films, Ian McDiarmid, walked onstage to loud applause from an audience of roughly 10,000 fans, many waving colourful lightsabres.

Director JJ Abrams, speaking alongside a handful of cast members, said the movie took place some time after the events of the 2017 film The Last Jedi.

The Rise of Skywalker will feature Daisy Ridley as the character Rey. ( Supplied: Lucasfilm via AP )

The footage showed a hug between Princess Leia, played by the late Carrie Fisher, and Rey (Daisy Ridley).

Fisher died in 2016, but Abrams said that in a "weird miracle", he was able to piece together unused footage from The Last Jedi to continue the beloved character's story.

"Princess Leia lives in this film in a way that's mind-blowing for me," he said.

The director disclosed little about the plot, however.

"This movie is about this new generation, what they've inherited, the light and the dark, and are they ready?" he told the crowd.

In an interview, Abrams told Reuters that writers met with Star Wars creator George Lucas before they started to script the final chapter in one of the world's most-celebrated movie franchises.

The goal was "to create something that gives a sense of surprise and thrill and heartbreak, and shock and awe, but also feeling like an inevitability," he said.

John Boyega returns for the final film as Resistance fighter Finn. ( Supplied: Lucasfilm via AP )

The circumstances surrounding Palpatine's return remain a mystery. The character appeared to die in 1983's Return of the Jedi.

In the trailer, the voice of Luke (Mark Hamill) says to Rey that "no-one's ever really gone".

Luke also tells Rey that "we have passed on all the knowledge" and the fight against evil is now hers.

Ridley, John Boyega, who plays Resistance fighter Finn and Oscar Isaac, who portrays pilot Poe Dameron, all attended the trailer launch.

Reuters