Paul McCartney Pens Beautiful Tribute To 'Fifth Beatle,' George Martin

Countless celebrities have come forward to pay their respects to legendary music producer Sir George Martin , who died on Tuesday night.

Sir Paul McCartney penned a beautiful tribute to Martin, who he referred to as the "fifth Beatle," in a loving Facebook post early Wednesday morning. 

"I'm so sad to hear the news of the passing of dear George Martin," McCartney wrote. "I have so many wonderful memories of this great man that will be with me forever. He was a true gentleman and like a second father to me."

The singer said that he regarded Martin as a "true friend" to himself and his family, adding that "if anyone earned the title of the fifth Beatle it was George."

"From the day that he gave The Beatles our first recording contract, to the last time I saw him, he was the most generous, intelligent and musical person I’ve ever had the pleasure to know," the Beatle wrote.

McCartney recalled one of his fondest memories with Martin -- when the music producer suggested the singer add a string quartet to the song "Yesterday." Though he was opposed to it at first, McCartney recognized that Martin made the track infinitely better, leading it to be one of the most recorded songs of all time .  

"I am proud to have known such a fine gentleman with such a keen sense of humour, who had the ability to poke fun at himself," McCartney wrote. "Even when he was Knighted by the Queen there was never the slightest trace of snobbery about him ... The world has lost a truly great man who left an indelible mark on my soul and the history of British music." 

Read the rest of McCartney's touching tribute below: 

Ringo Starr also paid tribute to Martin, tweeting out a sweet message on Tuesday night: