Paul McCartney and Others React to George Martin's Death

"He was a true gentleman and like a second father to me," McCartney wrote.

— -- Famed producer and "Fifth Beatle" Sir George Martin has died at the age of 90.

He continued, "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. 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."

Starr did the same on Twitter, sharing an old photo with the caption, "Thank you for all your love and kindness George peace and love."

But it wasn't only his former mates that paid homage to the gifted producer.

Here's what others had to say: