In an industry that worships at the altar of youth, it is hardly surprising that the Hollywood elite can be flexible with the truth when admitting their age. Most of the time it is met with an unconcerned shrug, another symptom of the ageist attitudes of the film business – especially when it comes to women.

But in 2015, Australian magazine Woman’s Day took such umbrage at actor and comedian Rebel Wilson supposedly being dishonest about being 29 years old that it published a piece calling her a liar. It described Wilson’s claim that she was a distant relative of Walt Disney as “pork pies” and also called into question whether Rebel was in fact her real name.

Wilson laughed it off at first, but then took the magazine to court for defamation when she realised the claims were losing her parts. During a colourful three-week trial in Melbourne, which ended this week, Wilson spent six days in the witness box defending herself against the “disgusting and disgraceful” allegations. And on Thursday, after deliberating for two days, the six-woman jury ruled entirely in her favour.

A defiant Wilson stood on the steps outside the supreme court of Victoria on Thursday and punched the air, beaming. “I had to stand up to a bully, a huge media organisation, Bauer Media, who maliciously took me down in 2015 with a series of grubby and completely false articles,” she said. Fellow Australian actor Russell Crowe also jumped in with immediate congratulations. “So brave, so much integrity – now fuck off back to Hollywood and be your brilliant self,” said Crowe, adding: “Proud of you.”

Before she was a victim of tall poppy syndrome in the Australian press, Wilson was a star on the rise. Having moved to Los Angeles from her native Sydney in 2009, she burst on to the Hollywood scene two years later in the comedy Bridesmaids, where her portrayal of the infantile flatmate Brynn managed to steal the film in just a couple of scenes. Her portrayal of bolshie Fat Amy in Pitch Perfect in 2012 seemed to secure her place as one of the ballsiest and most original comedy talents around.

Yet she said she was driven to take her defamation claims to court after several film contracts, including one for Kung Fu Panda 3, were cancelled following publication of the article. While her career has picked back up over the past year, in Wilson’s own words “they took those two years away from me doing what I love, which is entertaining people and making people laugh … I’m a person that’s really confident in my own skin and really felt like it was the right thing to do to take this company on.”

Wilson may have built a reputation for saying the unsayable – hosting the MTV awards she delivered, poker-faced, the line: “I could play black! I’m really into fat white chicks” – but, growing up in the western suburbs of Sydney, she was a quiet wallflower of a child.

She has admitted to being “cripplingly shy” and described herself as “borderline social-disorder shy. I was a total Nigel No-Mates.” Her mother, Sue, a teacher, was inspired to call her daughter Rebel after one of her young pupils who had sung the Carpenters’ We’ve Only Just Begun at their wedding. However, after pressure she gave her daughter the legal name of Melanie, though in the family she was always known as Rebel, and the comedian changed it officially in 2002.

Wilson was the eldest of four, with two younger sisters and a brother. Her mother and father both bred beagles and she often accompanied her mother around the country visiting dog shows. She was fiercely academic, and hid herself away in the library until the age of 14 when she became concerned her life would remain pathetic for ever. She joined the basketball team, became deputy head girl and discovered a talent for comedy, having been reluctantly dragged by her mother to community acting classes.

Her most formative theatrical experience came aged 17, when, during a year abroad in Zimbabwe, she contracted malaria and was admitted to intensive care. In her feverish state, she hallucinated winning an Oscar. “I went up there and gave an acceptance rap instead of an acceptance speech, and it brought the house down … The image was so vivid and strong that when I came out of the illness, I saw it as a sign: I knew I had to become an actress.”

Wilson had already been admitted to the top law school in the country, and to appease her parents she decided to go while studying at a youth theatre at the same time. She achieved small-scale success in Australia but in 2009 decided to make the jump and move to LA. Her curvaceous figure and dark, deadpan humour stood in opposition to the norms imposed on women in Hollywood, but Wilson is adamant they worked in her favour.

“I feel really lucky to be the body type I am,” she told Cosmopolitan magazine. “Being unique and different was a really good thing. When I walked into my agent’s office for the first time [in 2009], they looked at me and said, ‘Wow, we have nobody on our books like you.’ And they signed me on my second day here.”

The only thing Hollywood is more obsessed with than age is weight, and Wilson’s size is often the first thing mentioned about her in the media, alongside questions over whether she has ever attempted to “slim down”. Yet she will happily say it has given her a comedic advantage “whereas so many women see it as a disadvantage”.

“I’ve always tried to use my brain to get places,” she said. “There’s so many glamorous people in Hollywood, I just never want to compete with that … even the men get their skin lasered.”

Wilson’s almost immediate success in Hollywood speaks to that. One of her first auditions was for Bridesmaids, and while she lost out on the part to Melissa McCarthy, director Paul Feig was so taken with her comedic talents that he and producer Judd Apatow created the role of Brynn for her. She was subsequently labelled as one of the biggest talents to watch in 2012 and given a leading part in the musical comedy Pitch Perfect.

The talkshow host Conan O’Brien, who worked as an executive producer on her short-lived comedy series Super Fun Night, put into words what made Wilson such a welcome addition to the contrived bubble of Hollywood.

“She’s authentic,” said O’Brien, who recalled that he couldn’t take his eyes off her in their first meeting. “And it’s harder and harder to find that authenticity when so many actresses have been taking improv classes since they were a foetus. In her quiet way, you can’t believe the balls on this girl. She has an incredible will, but she’s completely unselfconscious in how she presents herself.”

Wilson was welcomed into the Hollywood fold with open arms and her ascension to an in-demand A-lister seemed assured. Jennifer Lawrence became her best friend and she shared a flat in LA with Matt Lucas, of Little Britain fame.

“When we met it was like complete synchronicity,” said Lucas. “We’re both very laid back and we’re also quite driven professionally and I see that in her and she sees that in me, but we’re not competitive because we just enjoy each other’s work.”

Yet in May 2015 the Woman’s Day allegations emerged, and were picked up by news outlets all over the world. She starred in the follow-up to Pitch Perfect but it wasn’t until last year, with roles in How To Be Single and the West End production of Guys And Dolls that her career has regained momentum. She has been cast in forthcoming remakes of Private Benjamin and Dirty Rotten Scoundrels, which will be retitled Nasty Women and will also see her take on a producing role.

Wilson, however, still revels in her outsider status to what she once described as the “insane” film industry and has no qualms about taking their values and standards to task. “Hollywood is ageist,” she said recently. “That’s why people do crazy shit to their faces – out of desperation to look younger. But I think my career is based more on my personality, so it doesn’t really matter.”