Kirstie Alley had many outspoken personas in her 40-year Hollywood career: comedic bombshell, Scientologist, Twitter warrior.

But over the past few months, the “Cheers” star had been quietly fighting colon cancer, which is known as the “silent killer” as often there are no symptoms until the disease is advanced.

It was her children, son True and daughter Lillie, who shocked the world with the announcement of the 71-year-old actress’s death on Monday night and paid tribute to their “incredible, fierce and loving mother.”

Alley spent the time she had left with her children and four grandchildren, the youngest of whom — True and wife Sara’s daughter Kit — was born in May.

True and Lillie revealed that doctors had “only recently discovered” the cancer and Alley had been receiving treatment at Moffitt Cancer Center in Tampa, Florida. She lived near Scientology headquarters in nearby Clearwater.

“She was surrounded by her closest family and fought with great strength, leaving us with a certainty of her never-ending joy of living and whatever adventures lie ahead,” the two said in a statement.

The Emmy winner enjoyed one final Thanksgiving with her family, asking her Twitter followers to name their favorite dish and boasting that she made the “best gravy in the world.”

Sources said Scientology leaders will hold a memorial service for Alley at the Flag Land Base in Clearwater. Raised a Methodist, she joined the church in 1979 to help put an end to her cocaine addiction.

As a longtime Scientologist — she made it to the highest level of learning, Operating Thetan Level VIII — there were immediate questions about the church’s role in her medical treatment following her death.

Alley is the third latest high-profile Scientologist to die in recent years from cancer. Actress Kelly Preston, 57, the wife of John Travolta, died of breast cancer in July 2020. Grammy Award-winning jazz pianist Chick Corea died at age 79 from a rare form of cancer in February 2021.

Tony Ortega, who writes the long-running Scientology blog The Underground Bunker, told Page Six that he had heard that Alley had suffered from back pain before being diagnosed with cancer, adding: “Scientology’s first book, ‘Dianetics,’ is built on the idea that most human ailments are psychosomatic and can be cured, so when Scientologists get ill, they are trained to first look for a Scientology solution.

“Scientologists know that [founder L. Ron] Hubbard was really down on doctors, so they look for alternatives.”

Alley did receive treatment, as did Preston.

“It’s nuanced,” Ortega added. “Scientology is against psychiatric care and psychiatric drugs. You lose your standing if you start using Lexapro, for example. But followers are not stopped from seeking medical treatment if they have cancer or anything like that. [The church] won’t tell you not to go to the hospital.

“They will often first try to take care of things through auditing — counseling — but as it has been pointed out, sometimes [people] go to the doctor when it’s too late and that can have tragic consequences.

“Did Kirstie’s training prevent her from seeking medical help sooner, maybe? A lot of people are asking.”

Actress and former Scientologist Leah Remini, who had a very public fallout with Alley after railing against the church, told Rolling Stone Tuesday: “While it has been reported that Kirstie sought conventional cancer treatment, which gave her a fighting chance, the majority of Scientologists do not seek treatment until it’s too late.

“Scientologists are convinced they can cure themselves of diseases like cancer. It’s one of the more sinister things they promise. And because Scientology claims to be an exact science, not a faith, its members are brainwashed into believing these false claims as guarantees.”

Page Six has reached out to the Church of Scientology for comment, as well as reps for Alley.

Alley, who grew up in Wichita, Kansas, joined Scientology after moving to Los Angeles. In her 2005 book, “How To Lose Your A** And Regain Your Life,” she recalled being hooked on cocaine — calling it “excellent powder” — thanks to a lover she called “Cowboy Carl.” The two dated after she split with her first husband, Bob Alley, in 1976.

The actress recalled how her drug habit got out of hand, leading to extreme anxiety attacks, insomnia, weight loss, and “psychotic thoughts.”

“I thought I was going to overdose almost every time,” she told Entertainment Tonight in 2012. “I would snort the coke, then I would sit there. I’d take my pulse [thinking], ‘I’m dying, I’m dying, I’m dying.’ Who would keep doing it?”

She was introduced to Scientology by a neighbor and enrolled at a Narconon center — Scientology’s rehab network that reportedly promotes long hours in a sauna and increasingly large intakes of vitamins.

She said it was “either the biggest scam in the universe or it would lead me out of my self-created hell.”

Alley added: “Miraculously, and I do mean miraculously, I had one Scientology session and never did cocaine again.”

After getting clean, her career took off with the NBC hit “Cheers,” for which she won an Emmy and a Golden Globe. She also co-starred in the 1989 box-office hit “Look Who’s Talking,” opposite fellow Scientologist Travolta, as well as two sequels.

Alley made it no secret that she had feelings for Travolta, telling Howard Stern: “It took me years to not look at John as a romantic interest.” She also called him “the greatest love of my life.”

She also revealed that Travolta’s wife, Preston, told her to stop flirting with him.

After her death this week, Travolta, 68, posted on Instagram: “Kirstie was one of the most special relationships I’ve ever had. I love you Kirstie. I know we will see each other again.”

Alley was married to “Hardy Boys” actor Parker Stevenson from 1983 to 1997. He has admitted that Scientology was a large factor in the split.

“Kirstie initially wanted us to mediate our property, support, and custody issues before a respected member of the Church of Scientology. I attended one five-hour meeting on December 28, 1996, and discovered that neither the mediator nor Kirstie had any knowledge of the law regarding the issues,” Stevenson said in a divorce affidavit, reported by Ortega. However, Stevenson paid tribute to his ex after her death, saying: “I am so grateful for our years together and for the two incredibly beautiful children and now grandchildren that we have. You will be missed.”

In 2018, Alley was featured in a church magazine called Freewinds — named after Scientology’s private cruise ship, which is said to be the only place members can achieve the highest level of “auditing,” OT VIII (Operating Thetan Level Eight).

“OT VIII is the highest you can go on the ‘Bridge to Total Freedom,’” Ortega told The Post. “It can cost between $1,000,000 to $2,000,000 to go all the way up and it can take you 20 years.

“Scientologists are told that, if they can reach OT VIII, they will be ’cause over matter, energy, space, and time,’ which translates to various superhuman abilities, including being impervious to disease.”

In the article, Alley was quoted as saying: “Now here I stand a new OT VIII, shiny, fresh, and calm.”

Alley’s feud with Remini also spilled over to ABC’s “Dancing with the Stars.” Alley had previously been on the show and was close friends with her dance partner Maksim Chmerkovskiy.  But when Remini was on the show in 2014 and became friends with Chmerkovskiy as well, he said Alley had appeared to cut ties with him because of it.

In February,  as Russia’s attacks on Ukraine heated up, Alley tweeted, “I don’t know what’s real or what is fake in this war. So I won’t be commenting. I’ll pray instead.” She later deleted it.

Chmerkovskiy, a Ukraine native who was stuck in Kyiv at the time, responded on his Instagram account:

“Dear Kirstie, we haven’t spoken in a while, but I clearly remember being right next to you while you were organizing trucks of aid during Hurricane Sandy and I remember all that you were saying to me about situations where innocent are suffering. That same energy is needed right now. No one needs your prayer if you don’t know what’s real or fake.”

Remini, meanwhile, pointed out that she wasn’t sure what Alley was referring to, since Scientologists don’t “pray” to anything.

In more deleted tweets, Alley appeared to hit back at both Chmerkovskiy and Remini, saying that Remini “shoots her mouth off and has an IQ of about 75.”

Following her death, Chmerkovskiy posted a photo of them dancing on Instagram, writing: “My dearest Kirstie, We haven’t spoken lately and I’ll tell you everything when I finally see you, but for now I want to say that I love you very much and I wish you the most peaceful rest.