*Professor E. Gadd, full name Professor Elvin Gadd (sometimes Dr. E. Gadd; Japanese: オヤ・マー博士 Professor Oya Mā), is the main deuteragonist and the elderly doctor/scientist that first appears in Luigi's Mansion and is the founder/owner of Gadd Science, Inc. A researcher of ghosts since his 20s, he is the creator of the Poltergust 3000, Poltergust 5000, and Poltergust G-00, which allow him and Luigi to capture ghosts.

He always speaks in ambiguous and weird gibberish (supplied by Kazumi Totaka, wh