Shefrin passed away in his sleep on 6 April (11) in Encinitas, California after a long battle with Parkinson's disease.
Throughout his showbusiness career, which spanned more than 40 years, Shefrin represented stars including Guy Lombardo, Dick Clark and Don Rickles, while he also organised the Beatles' first New York appearance at Carnegie Hall in 1964.
He also helped launch the writing career of moviemaker Woody Allen in the 1950s by hiring him as a school student to write witty comments to be sent to gossip columnists and attributed to Shefrin's clients. Allen remembered his former mentor more than 40 years later by handing Shefrin a small part in his 1994 film Bullets Over Broadway.
Shefrin is survived by his wife, Sophie, and son, Paul.