'Full security detail': Terrifying reality of Laura Dern's Ellen appearance

Laura Dern guest-starred in the iconic coming out episode of Ellen DeGeneres' sitcom. Photo / YouTube.

Laura Dern has revealed she needed a "full security detail" after appearing in the iconic coming out episode of Ellen.

The 52-year-old actress has hailed playing a lesbian who helped the titular character - played by Ellen DeGeneres - realise she was gay as the "greatest thing" she's ever been part of.

The two-part episode aired April 30, 1997, and saw Ellen become the first gay character to lead a television show. The groundbreaking storyline went on to win the sitcom a Peabody and Emmy Award.

DeGeneres and Dern in the groundbreaking episode. Photo / YouTube.

However, Dern says she was warned not to take the role by people who were "worried" about the impact it would have on her safety and career.

"A lot of people in my life really worried," said Dern. "I grew up in a bubble and didn't realise we weren't there yet or something.

"Greatest thing I could've ever been part of, honestly. An incredible honour....I was excited. I didn't think twice about it. It was a great opportunity. And then the calls started coming in once I'd said yes, from a couple of advisers in Hollywood who were out gay men, [telling me] to not do it. A lot of people in my life really worried. And I was like, 'This is ridiculous.' "

Dern only realised that not everyone was accepting when there was a bomb threat on set that forced both her and fellow guest star Oprah Winfrey to be evacuated.

"We only did it for what, 10 days? We all spent the next couple of years really struggling in work and safety," she told Vulture. "It was radical to experience that. It was the only time I ever experienced having to have to have full security detail."

Although the Big Little Lies star didn't work for a year afterwards, the "gift" of the role offered her valuable insight which has influenced her ever since.

"It's shaped and continues to shape who I am as an advocate, as an activist, as a parent," she said.

"It's a profound thing when you see someone bring their truth, but also all the layers of shame and fear that have been put onto you because of feeling like the other, whatever your experience is. So I'm forever grateful."