Carrie Fisher's daughter has made an emotional tribute to her mother in front of legions of fans at the official Star Wars convention.

Billie Lourd, who appeared alongside her mother in The Force Awakens, struggled to hold back tears as she spoke of her mother's strengths and vulnerabilities at the start of the four-day Star Wars Celebration in Orlando, Florida.

Star Wars mastermind George Lucas and Hollywood legend Harrison Ford made surprise appearances at the first event on Thursday, held to mark 40 years since the first movie in the saga hit cinemas.

But it was Fisher, who died unexpectedly in December, who leant the event extra emotional heft for fans.


Sometimes pausing and sighing heavily into the microphone to keep her emotions in check, Lourd's speech in tribute to her mother was equal parts hilarious and heartbreaking.

"My mom used to say she never knew where Princess Leia ended and Carrie Fisher began," Lourd said.

"She went from being an unknown actress, the daughter of Debbie Reynolds and Eddie Fisher, to Princess Leia, a character synonymous with the idea of the ultimate strong woman: a soldier, a fighter, a beyond-capable, independent, sensible woman in control of her own destiny, a rebel who resisted the norm.

"She was imperfect in many ways, but her imperfections and willingness to speak about them are what made her more than perfect."

Lourd told the crowd of Star Wars fanatics that Fisher had a special understanding with them.

"My mom, like Leia, was never afraid to speak her mind and say things that might have made some people uncomfortable. But not me, and not you," she said.

"That was why she loved you because you accepted and embraced all of her.

"The strong soldier of a woman she was and also the vulnerable side of her who often openly fought her own dark side, knowing early on that we all have a dark side of our own, whatever it may be."

When discussing the things her mother had taught her, Lourd provided the highlight of her speech.

To the delight of fans, she launched into a word-perfect impression of her mother's famous monologue from the first movie that ends in the immortal line "Help me Obi-Wan Kenobi, you're my only hope". The crowd loved it.

"I learnt by knowing her that the most evolved person is seemingly a contradiction," Lourd said.

"They're both the strongest and the most vulnerable person in the room. And that was her. That is Leia.

"Thank you for loving her and carrying on what she stands for. I'm beyond grateful."

Lucas, who catapulted Fisher into Hollywood immortality when he cast her as Princess Leia, said she embodied everything the character represented: strength, humour and intelligence.

The director said she could more than hold her own against her co-stars, Ford and Mark Hamill, who also appeared at the Star Wars Celebration on Wednesday.

"She was a princess, she was a senator, she played a part that was very smart and she was having to hold her own against two big lugs, these goofballs that were screwing everything up," Lucas said.

"But she was the boss, it was her war and when I cast it I said I want somebody young to play the part ... and when Carrie came in, she was that character. She was very strong, very smart, very funny, very bold, very tough and, you know, there really wasn't much of a question. There are not very many people like her.

"(She was) one in a billion. And for this particular part, it was absolutely perfect because she could hold her own against anything.

"She wore a dress through the whole thing but she was the toughest one of the group.

"And that's the key to Carrie being able to play that part. It was a hard part to play and she pulled it off brilliantly, and it really shows the level of her talent and, at the same time, she was fun to be with.

"But she was brilliant and obviously we'll all miss her, but she'll always be the princess who took command and never backed down, never was in jeopardy. She was always helping the other guys get out of the messes they created."

Fisher died of cardiac arrest in December after completing the filming on the next Star Wars movie, The Last Jedi.

Fans are expected to get the first look at Episode XIII on Friday when the Star Wars Celebration continues. The movie is expected to be released in Australia in mid-December.