Maestro D'Elfman was a conductor and likely composer who was a member of the Society of Explorers and Adventurers at some point during the 19th century. He was considerably close with Lord Henry Mystic and appeared to have assisted him with his music-room in Mystic Manor.
Maestro d'Elfman appears in portrait form in Mystic Manor, showing him situated within Mystic's music room. Later in the attraction, guests traverse this music room following its possession from the Balinese Music Box.
Trivia
Despite being one of the first S.E.A. members introduced and actually visualized, d'Elfman probably contains the least amount of attraction references of any society member.
For unknown reasons, the maestro was not present for the S.E.A. meeting of 1899.
It is possible he was simply unavailable.
Another possibility is that he died prior to this meeting.
It is also possible that he was simply not a member at the time of the meeting in 1899.