The Dungeon Master: The Disappearance of James Dallas Egbert III is a 1984 book by private investigator William Dear.

It relates Dear's explanation of the 1979 "steam tunnel incident" in which James Dallas Egbert III, a student at Michigan State University, disappeared.

Egbert was a 16-year-old child prodigy who was battling intense academic pressure, drug addiction, and personal issues.

This theory was taken as fact by the media and caused intense controversy over the psychological effects of role playing games.

Dear kept the true circumstances of the disappearance a secret until four years after Egbert's death, due to a promise he made to the boy not to reveal them.