Main Theme (Luigi's Mansion)

The "Main Theme" is a musical theme composed for Luigi's Mansion by Kazumi Totaka. It is an eerie piece played in A minor at a moderato tempo, and is usually associated with the Luigi's Mansion series and Luigi himself. A different arrangement of the Main Theme is often used as Professor Elvin Gadd's theme throughout his appearences.

Luigi's Mansion
The theme debuts in Luigi's Mansion as the background music for the mansion that plays when Luigi is in a dark hallway and not actively engaged in combat. He may hum the theme as it plays. When Luigi enters a lit room, the music is silent while he whistles the theme. A different arrangement plays in E. Gadd's Lab.

Luigi's Mansion: Dark Moon
In Luigi's Mansion: Dark Moon, two different arrangements of the Main Theme exist: one played on a compressed synthesizer is the ringtone for the Dual Scream, and another played on a violin melody and oboe harmony is for when E. Gadd is actively calling Luigi through the Dual Scream. Both of these variations play the theme in B♭ minor instead, though the former plays it in an allegro tempo. Another arrangement of the theme's motif in A♭ minor is briefly used when E. Gadd prompts Luigi to use the Dark-Light Device to free Mario from his painting, which ends in a B diminished triad.

Luigi's Mansion 3
Two additional arrangements of the theme appear in Luigi's Mansion 3: one consists of a compressed square synthesizer melody played in C minor and an allegretto tempo, and is used for the Virtual Boo's ringtone; the other is a slow jazz arrangement played in B♭ minor, and plays while Luigi is inside E. Gadd's lab in the Garage.

Mario & Luigi: Superstar Saga / Mario & Luigi: Superstar Saga + Bowser's Minions
In Mario & Luigi: Superstar Saga, an arrangement of the Main Theme arranged by Yoko Shimomura plays during some of the cutscenes with Professor E. Gadd in the Starbeans Cafe, more specifically during the ones where the lights are out. In the remake, Mario & Luigi: Superstar Saga + Bowser's Minions, the same version of E. Gadd's theme from Luigi's Mansion: Dark Moon is used instead for all cutscenes.

Mario & Luigi: Partners in Time
In Mario & Luigi: Partners in Time, an arrangement of the theme plays during cutscenes involving E. Gadd.

Super Smash Bros. Brawl
In Super Smash Bros. Brawl, an orchestral arrangement of the Main Theme was arranged for the Luigi's Mansion stage by HAL Laboratory composer Shogo Sakai. During the second half, a pipe organ plays the backing melody while a choir vocalizes the theme. A Western-styled version of the theme littered with fermata-induced rests appears during Luigi's introduction in the Subspace Emissary.

The song returns for the same stage in Super Smash Bros. for Wii U, and for every Mario-series stage in Super Smash Bros. Ultimate (titled "Main Theme - Luigi's Mansion (Brawl)").

Super Smash Bros. for Wii U
In Super Smash Bros. for Wii U, the theme was incorporated into "Luigi's Mansion Series Medley" which was arranged by Bandai Namco composer Hiroyuki Kawada. This medley also uses the version heard in E. Gadd's Lab. The arrangement plays on the Luigi's Mansion stage and returns in Super Smash Bros. Ultimate for any Mario-series stage.

Super Smash Bros. Ultimate
Another, orchestral arrangement was created for Super Smash Bros. Ultimate by Nintendo composer Maasa Miyoshi, which also uses the version heard in E. Gadd's Lab. Compared to the previous installments' arrangements, this arrangement is more fast-paced, and also incorporates the title theme, the option selection sound effect, and the credits theme.

Mario Party 10
In Mario Party 10, an arrangement plays during Luigi's turn in amiibo Party.

Mini Mario & Friends: amiibo Challenge
In Mini Mario & Friends: amiibo Challenge, two arrangements play in the levels of Moonlight Mansion. The first one is faithful to the melody of the original, while the second incorporates the beat heard in Warped Mansion's [[Media:MvDKMLM WarpedMansionC.oga|third track]] from Mario vs. Donkey Kong: Mini-Land Mayhem!