But it was a moment after Monroe sang at Madison Square Garden in honor of the president's 45th birthday that is attracting attention.
A black and white image, which is now up for sale, is the only known photograph of Kennedy and Monroe together, perhaps because of the rumors of an affair that have swirled for 50 years.
In the photo Monroe, wearing the same dress she performed in, is speaking to President Kennedy, whose head is tilted slightly and looking down while listening to her. His brother, Robert Kennedy, is standing next to the pair looking on.
Singer Harry Belafonte is in the background and historian Arthur Schlesinger Jr., who served as an advisor in the Kennedy White House, is standing off to the side smiling.
The photo was snapped at a private party at the Manhattan home of Arthur and Mathilde Krim, according to filmmaker Keya Morgan who owns the print. He said the existence of the image was kept a secret for decades.
"The Secret Service had specific instructions not to photograph President Kennedy and Marilyn together because it would have been a national scandal," Morgan said.
The only photographer that was allowed into the party was Cecil Stoughton, the White House photographer and the person who snapped the photo.
Stoughton took several photos at the party, but once President Kennedy saw the camera, he turned his head towards the wall, Morgan said.
Later the Secret Service asked Stoughton to give them all of his photos of Kennedy and Monroe.
Secret Service Asks For All of the Photographs
"He handed over all those negatives and photos. There [were] multiple ones," Morgan said. "And the only one that survived, ever, was that one that was in the dryer, you know, where they were drying the negative, and he kept it a secret for decades, decades and decades."
Morgan said he believes Stoughton kept the image a secret for all those years out of politeness for Jackie Kennedy, the president's wife.
"He was very close with Jackie and he said he did not want to do anything to really hurt her and upset her," Morgan said.
The filmmaker bought the photo and dozens of other lesser known images from Stoughton for approximately $50,000 for a documentary about Monroe sometime in the early 2000s.
The image of the Kennedy brothers and Monroe is only one of 10 prints that exists from the negative. Morgan is now selling it for $23,000. He will also sell one of Monroe's rings and her watch, which was made from three types of gold, for $275,000.
"You know, Marilyn died within months. President Kennedy died the next year and Bobby a few years from that. So what a haunting photograph, and it's the only one of any of them together," Morgan said.