When Barbara Davis comes knocking, Hollywood always answers, that includes George Clooney and Frank Sinatra.

“The Carousel of Hope Ball is a real testament to her,” Clooney says. “She’s able to really put together a great group of people who all love her. Obviously, a big part of this is that you don’t want to disappoint her. She works so hard at this, and she’s really good at it. And I really care about her. She’s a really nice, smart, hardworking woman who I believe very much in.”

Clooney will be on hand to keep Variety ‘s Philanthropist of the Year happy (and accept her Brass Ring Award for “unprecedented humanitarian undertakings”) at Davis’ gala Oct. 20 at the BevHilton.

It’s the legendary fete that has raised more than $75 million in the past 35 years for the octogenarian’s two personal causes, the Children’s Diabetes Foundation and the Barbara Davis Center for Childhood Diabetes, both established in Denver after she and her late husband, billionaire businessman and one-time 20th Century Fox owner Marvin Davis, discovered their daughter Dana had childhood diabetes. It’s the huge party that Davis only puts on every other year, because of its massive size.

Arguably the biggest philanthropic event held in this town, Davis’ bash always draws A-list celebrities and power players from every era, as 2012’s “blue ribbon committee” proves, boasting Sidney Poitier, Tom Cruise, Scarlett Johansson, Leslie Moonves, Barbra Streisand, Brad Grey, Denzel Washington and a host of others.

And it’s an eclectic group. Always.

Davis recalls, “The year Michael Bolton — he’s adorable — sang at the Carousel Ball, he was going with Nicollette Sheridan. I remember the president, Ronnie Reagan, was sitting next to me, and then Nancy and opposite us was Michael and Nicollette, and they were continually making out at the table! And Ronnie said to me, ‘Can you believe it? I can’t look any further than right in front of me!’ Anyway, they broke up later.”

No wonder everyone in Hollywood wants to attend, even the newest kids on the block who have probably all heard the oft-said adage about this party, that “women who go to the Oscars borrow their jewels, but women who go to the Carousel of Hope simply open their safe-deposit boxes and take out their own statement pieces to wear.”

“It was many years ago that I went, and I was really intimidated by it,” Clooney says, recalling the 1996 gala. “Everybody was a big star, and I had been famous for about five minutes at that point. I was very intimidated by how many famous faces were there. I had never been to the Oscars, never been to anything like it before. So for me, that was the biggest event I had ever been to and I was very impressed by it.”

And Davis’ Carousel of Hope continues to impress, especially since Clive Davis (no relation) joined forces with the hostess with the mostest in that same year, signing on as her music chairman.

“When she asked me to recruit Whitney Houston for the Carousel Ball in 1996, I obeyed the command!” jokes the famed recording executive. “Whitney immediately responded affirmatively and the three of us got to know each other very well.”

Even prior to her ongoing relationship with Davis, she’d already established the Carousel as the one fundraiser where top musical acts always performed, with Frank Sinatra leading the pack.

How does she get such headliners?

“I call everybody myself,” says Davis. “I call their publicists, I call their managers, I call their agents. And the ones that I know, like J. Lo and Marc Anthony last time, I know them, so I just called them and asked.”

Regarding Sinatra, she didn’t even have to ask.

“We had a house in Palm Springs, we used to go every weekend. And the Sinatras were on one side of us and the Annenbergs were here, on the other,” Davis recalls. “So … one night Frank said to Dana, she was 7 years old, ‘Why don’t you tell your mom to have a party with a lot of people, and I’ll sing at the party and they will pay a lot of money.’ And Dana said, ‘Who would pay to listen to you sing?’ He was just our neighbor! And he did come, and he sang three times at the event.”

Showbiz Philanthropy Leader Report:
Barbara Davis: Philanthropist of the Year | HFPA shares its Golden Globes wealth with arts orgs | At 70, Foreign Press org expands its reach | Newman legacy at Weinstein Co. | Hollywood goes global to help a continent in need
The Variety Guide to Entertainment Philanthropy