Elizabeth Taylor had one last "romantic friendship" with a Hollywood star 40 years her junior.

It was 2009 when Colin Farrell met Tim Mendelson, the assistant to the legendary actress, at Cedars-Sinai Hospital in Los Angeles, California. She was having a heart procedure and the actor was awaiting the birth of his son. After getting home, Farrell couldn’t stop thinking about Taylor, and he quickly arranged a visit.

"I love the story of Elizabeth and Colin Farrell because they had this amazing … last romantic friendship in Elizabeth’s life," bestselling author Kate Andersen Brower told Fox News Digital.

Elizabeth Taylor wearing a green dress when she was young

Elizabeth Taylor, who passed away in 2011 at age 79, is the subject of a new book by bestselling author Kate Andersen Brower. (Silver Screen Collection/Getty Images)

Brower has written the first authorized biography on Taylor, which was published on Dec. 6 and titled "Elizabeth Taylor: The Grit & Glamour of an Icon." With the blessing of Taylor’s family, Brower had access to more than 7,000 letters and personal notes, as well as unseen archives.

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She also interviewed 250 of Taylor’s loved ones and acquaintances, including Taylor’s four children and her many lovers, including her last surviving husband, former Sen. John Warner, who initially gave Brower the green light to write the book about his ex-wife before his death in 2021 at age 94.

Brower made several surprising discoveries along the way, including Taylor’s deep bond with the dashing leading man. Following Taylor's death, Farrell, now 46, spoke about the relationship with Ellen DeGeneres.

Elizabeth Taylor and Colin Farrell smiling with her dog

Kate Andersen Brower said Colin Farrell brought Elizabeth Taylor great joy during the final years of her life. (Chris Wilding, Elizabeth Taylor's son)

"Colin loved to joke with her," Brower said. "He would go to her house in Bel Air, and he would pull down his pants and show her his tattoo, which was close to his crotch area. And she just loved that because he reminded her of Richard [Burton]."

Taylor, who led a successful decades-long career from child star to screen siren, passed away in 2011 at age 79. The Academy Award winner, who appeared in more than 50 films and raised awareness of the AIDS crisis, also stirred headlines with her eight marriages to seven men. Many have argued that Taylor’s true love was Burton, the Welsh actor who became her husband twice.

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According to Brower, Taylor was intrigued by Farrell, who reminded her of "her beloved Richard." The pair bonded over poetry, as Taylor once did with Burton. They even played recordings of Burton reciting poetry. Farrell later described how Taylor would close her eyes and "relive her life with him." She wrote to Farrell, "You remind me of so many good things … so many happy things."

Colin Farrell speaking with the media

Colin Farrell opened up to Ellen DeGeneres about his relationship with Elizabeth Taylor in the final years of her life. (Phillip Chin/WireImage)

"I fell in love with her," said Farrell, as quoted by Brower’s book. "In my short time with her, I got a sense of how magical it may have been to have loved her in a romantic way, and to have felt the romance of her romantic love."

Brower shared that Farrell would sometimes call Taylor at 2 or 3 in the morning, and she would happily chat with the star. Hundreds of texts were also exchanged during their two-year-long friendship. At one point, Taylor’s grandson, Quinn, began calling Farrell "Papa Colin."

"You know, he’s Irish, Richard was Welsh," said Brower. "But [he’s] a brooding, dark, handsome man who’s fearless. [There’s this] … raw sexuality that I think both Richard and Colin shared that was very attractive to her. … I think it maybe even gave Elizabeth more years, having that friendship towards the end of her life and being able to talk to somebody who was vibrant and reminded her of the great love of her life – [it] probably helped elongate her own life."

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Mark Anthony (Richard Burton) admits his love for Cleopatra (Elizabeth Taylor) in film, Cleopatra.

Elizabeth Taylor met Richard Burton before they worked together in "Cleopatra." She wasn't impressed by the Welsh actor. But that all changed. (Getty Images)

When it came to Burton, it wasn’t love at first sight. They first met at a party a decade before while filming 1963’s "Cleopatra." Taylor, who was aware of Burton’s womanizing reputation, refused to be "a notch on his belt." On the set of the epic drama, the unimpressed Taylor found the heavy drinker to be "a slob" and "a mess." But sparks quickly flew between the pair, who were both married, as they brought the sweeping romance to life. The affair intensified publicly, and the paparazzi, still in their early days, were eager to capture any moment of the scandal. The Vatican condemned the co-stars and publicly denounced their "erotic vagrancy."

Elizabeth Taylor and Richard Burton fighting in a movie scene

Welsh actor Richard Burton and British-American actress Elizabeth Taylor on the set of "Who's Afraid of Virginia Woolf?" The couple was nicknamed "The Battling Burtons" by the press. (Sunset Boulevard/Corbis via Getty Images)

The relationship was passionate, fueled by sex and screaming matches. Taylor was already coined a "homewrecker" for being at the center of Debbie Reynolds and Eddie Fisher’s breakup in 1959 before the singer married her that same year. Burton had already subjected his wife, Sybil, to numerous infidelities. But letters read by Brower revealed that despite the pair being so enraptured with each other, their love had a dark side.

"I think Richard Burton and Elizabeth Taylor couldn’t make things work because they were both addicts," Brower said. "She was addicted to painkillers her whole life. She’s also the first celebrity to talk about going to Betty Ford. Her son told me, and this is the first time her kids have talked to a journalist about their mother in such a personal way, he described their relationship and said it was hard to notice his mother’s addiction because it was like a barbecue and the house behind it was fully engulfed in flames. Richard’s alcoholism was so all-consuming."

Richard Burton and Elizabeth Taylor drinking

Elizabeth Taylor's passionate romance with Richard Burton was fueled by addiction, said Kate Andersen Brower. (Keystone/Getty Images)

"And Elizabeth had a streak in her that is very difficult to talk about, which I think a lot of addicts have in these relationships, where Richard was trying to stop drinking, but she didn’t recognize who he was when he was sober," she continued. "And so, she would give him little bits of gin when he was trying not to drink because she didn’t want to see him in pain. He was going through withdrawal – shaking, very sick, sweating. And so, she would just give him a little bit. … That’s not what you do with an alcoholic because they have to stop completely. … It was a complicated relationship. They fought all the time. They made up, and they had this passionate sex life. … But I think they also hurt each other a lot."

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Elizabeth Taylor and Richard Burton on their wedding day

Elizabeth Taylor and Richard Burton kiss at their first wedding in Montreal, Canada. They married twice, but both marriages ended in divorce. (William Lovelace/Evening Standard/Getty Images)

Taylor and Burton were married between 1964 and 1974 and again from 1975 until 1976. Three weeks before his death in 1984 at age 58 from a brain hemorrhage, Burton told his brother, Graham, "Elizabeth and I never really split up. And we never will."

Burton wrote Taylor one last letter days before he passed away. He described how he was at his happiest with her. Burton also wondered if they might have had another shot together. Taylor kept the note in a bedside drawer until her death.

Elizabeth Taylor and Richard Burton in bed together

Kate Andersen Brower strongly believes Richard Burton was the great love of Elizabeth Taylor's life. She's also adamant that the pair would have married a third time. (Bob Penn/Gamma-Rapho via Getty Images)

"When Richard passed away, Elizabeth was completely devastated," said Brower. "And the worst part for her was that she couldn’t go to his funeral because his wife at the time did not want Elizabeth there. She thought that Elizabeth would make it all about her. … But Elizabeth truly loved Richard. … To her, they were partners in life, and they probably would have married a third time. His wife was jealous and upset and still holds on to a lot of resentment. I’ve talked to her about this feeling that Elizabeth had ownership over Richard. … She always felt Richard’s family liked Elizabeth more."

Another revelation Brower made in her book is that while Taylor was married to her second husband, Michael Wilding, between 1952 and 1957, she had an affair with Frank Sinatra. According to the book, Taylor allegedly became pregnant with the singer’s child. She wanted to divorce the actor and marry the crooner, but he "didn’t want any part of that." Sinatra’s manager allegedly put Taylor in a limousine that drove her to Mexico where she had an abortion.

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Elizabeth Taylor and Frank Sinatra speaking with the public

Elizabeth Taylor and Frank Sinatra circa 1982 (Diana Walker/Liaison)

"Elizabeth never forgave Frank Sinatra for abandoning her after she was pregnant with his child," Brower said. "It was very emotional for her. But I think eventually she was able to develop a sort of friendship with Frank Sinatra because there are letters between them that are sweet. … I think that they eventually moved on as the years went by. This is when she was really young. … As she had all of these loves in and out of her life, she was able to move on."

Brower hopes that her book will give readers an in-depth look at a "survivor" who proudly lived – and loved – on her own terms.

Elizabeth Taylor smirking

Kate Andersen Brower hopes her book will show the many different sides to the Hollywood icon. (Michael Putland/Getty Images)

"I think I was most surprised about Elizabeth’s many sides," said Brower. "How multifaceted she was. She wasn’t just a movie star. She wasn’t just an activist or an entrepreneur. She was not just a courageous person. She also had a lot of fear and vulnerability in her life. A lot of the letters showed her begging Richard Burton to stay with her, wanting to stay married to him. … This sense of always looking for love and fulfillment and never completely getting it. … She was so unapologetic in who she was and what she desired."