Doris Day, who used her girl-next-door good looks to charm American audiences during a decades-long acting and singing career, died Monday.

She was 97.

Best known for her wistful song "Que Sera, Sera," Day passed away surrounded by close friends at her home near Carmel Valley, California, the Doris Day Animal Foundation said in a statement.

She "had been in excellent physical health for her age until recently contracting a serious case of pneumonia," according to the foundation.

Day, who turned 97 on April 3, broke into show business as a singer, and recorded a hit, "Sentimental Journey," with bandleader Les Brown in 1945. That and “Que Sera, Sera” — which Day performed in Alfred Hitchcock's 1956 thriller "The Man Who Knew Too Much" — were her biggest chart-toppers.

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The multitalented Day would jump off the turntable and on to the big screen, with credits in 39 movies. Her best-known screen works include "Calamity Jane" in 1953, "Love Me or Leave Me" in 1955, "The Man Who Knew Too Much" in 1956, "Pillow Talk" in 1959, "Lover Come Back" in 1960 and "Move Over, Darling" in 1963.

"During her three decades of work in film, Day starred in nearly every genre, not just as a singer/dancer but as an actress with superb comic timing, a natural talent for interpreting a role and a gift for evoking emotion," her foundation said.

Paul McCartney paid tribute by saying he had visited Day several times at her California home, "where her many dogs were taken care of in splendid style."

"So sad to hear of Doris Day passing away. She was a true star in more ways than one," the former Beatles legend said in statement. "She had a heart of gold and was a very funny lady who I shared many laughs with."

The famed musician added, "I will miss her but will always remember her twinkling smile and infectious laugh as well as the many great songs and movies she gave us. God bless Doris."

Day was the first Hollywood star many of America's Baby Boom generation ever knew.

"For those of us in my generation, Doris Day was synonymous with Hollywood icon," actor George Takei said in a statement. "She would no doubt remind us, upon this day of her passing, 'Que sera sera,' but we will miss her dearly anyway. Rest now in our hearts forever, Ms. Day."

Day was married four times, which conflicted with her squeaky-clean public and big-screen persona. In her 1976 book, "Doris Day: Her Own Story," the actress said her real life was much more complicated.

With three bad marriages in her rear-view mirror at the time, Day said couples should live together before walking down the aisle — a risque, forward-thinking stance at the time.

"I have the unfortunate reputation of being Miss Goody Two-Shoes, America's Virgin, and all that, so I'm afraid it's going to shock some people for me to say this, but I staunchly believe no two people should get married until they have lived together," she wrote.

Doris Day with Rock Hudson in a scene from the 1955 film "Pillow Talk." dpa via AP Image

Doris Mary Ann von Kappelhoff was born April 3, 1922, in Cincinnati, the child of Alma Sophia Welz and Frederick Wilhelm Von Kappelhoff, who was a music teacher.

The youngest of three kids, Day was named after silent movie actress Doris Kenyon.

While Day never won an Oscar, she was honored with a Presidential Medal of Freedom in 2004.

President George W. Bush declared that it was "a good day for America when Doris Mary Ann von Kappelhoff ... decided to become an entertainer."

The humble Day didn't understand all the fuss when Bush announced she'd be honored.

“My first reaction was, ‘For what?' " she said after receiving the news. “I’m not being coy or looking for a laugh. I have never thought about awards, whatever I do.”

In her post-entertainment career, Day directed most of her energy into animal rights, through her Doris Day Animal Foundation and the Doris Day Animal League.

The Doris Day Animal League donated $1.5 million to Amendment 13, the ballot initiative against dog racing that scored a surprising win at Florida's ballot box this past November.

"It is with profound sadness that we say goodbye to our friend Doris Day, legendary actress, singer, & fierce animal advocate," the Humane Society of the United States said in a statement. "Though she will be missed, we can't thank her enough for her admiration & devotion to animals."

The legendary entertainer's "wishes were that she have no funeral or memorial service and no grave marker," according to her foundation's statement.