Bobby Darin was born Robert Walden Cassotto in the Bronx in 1936. Like many entertainers of the period he thought he would have a greater chance of success if he did not use an ethnic name. Darin was a name he found in a phone book.
He didn't get his name from a phone book. Apparently he saw a sign for a night club and took the Darin out of that - see Beyond the Sea with kevin spacey, also the Biography channel has a brilliant one hour bio of him which they show. He was the best! No one can sing Mack the Knife or La Mer like him. He was a loss.