Characters:

Playable:

Luigi - Main Protagonist

Gooigi

Supporting:

Professor E. Gadd

Polterpup

Toads

Mario

Antagonists:

King Boo - Main Antagonist

Enemies:

Boos

See: List of Boos in Luigi's Mansion 4

Snuck (HP 10) - Comparable to Goobs and Greenies from past games.

Sumo (HP 50)

Shadow (HP 70)

Genius (HP 65)

Bosses:

Possessors (HP ---) - Controls other beings or objects to attack Luigi!

King Boo (HP 300 [100 each phase]) - Final Boss