The Answer
He’s named after a 19th century German composer.
It’s hard to imagine anyone would choose to name themselves Engelbert Humperdinck, but that’s exactly what singer Arnold George Dorsey did. At the age of 29, after failing to achieve success under the name Gerry Dorsey, he signed with a new manager Gordon Mills.
Mills was already managing a singer named Tom Woodward who was persuaded by Mills to change his name to Tom Jones after the 1963 film starting Albert Finney (based on a novel by Henry Fielding).
Rather than going with a literary or film reference again, he went with a different approach for Dorsey. Engelbert Humperdinck is the name of a German composer from the 19th century, famous for composing the opera Hansel and Gretel.