John Lennon's birthday remembered in sweet tributes by Yoko Ono and Paul McCartney

Yoko Ono and Paul McCartney posted touching tributes celebrating Beatles legend John Lennon's birthday.

"Happy Birthday John! Happy Birthday Sean!​" Ono said in an Instagram post, also wishing a happy birthday to her son Sean Lennon. "I love you! ​yoko."

McCartney posted a throwback picture, writing in the caption: "Happy Birthday thoughts for @johnlennon."

Lennon would have turned 81 on Saturday. Last year marked the 40th anniversary of the singer's death. He was shot and killed on Dec. 8, 1980, as he and his wife, Yoko Ono, were heading toward his New York City apartment building.

The gunman, Mark David Chapman, was convicted and remains in prison.

McCartney remembered the anniversary in a Twitter post. "A sad sad day but remembering my friend John with the great joy he brought to the world," he tweeted. "I will always be proud and happy to have known and worked with this incredible Scouser! X love Paul."

Ono also remembered the anniversary, writing that it was a "hollowing experience."

"After 40 years, Sean, Julian and I still miss him,” Ono said, referring to Lennon’s two sons.