The Mystery Man is an unofficially-named, unidentified man limping in a business suit. He first appears in an ending for The House of the Dead III, and later in endings for The House of the Dead 4 and Special.
The Mystery Man's first appearance is in one of the endings of The House of the Dead III. He enters the chamber where the Wheel of Fate was defeated, picking up a glowing canister that was revealed earlier as Daniel's cure. Chuckling to himself, he says "It appears that he didn't understand its true purpose," before leaving.
In an ending for The House of the Dead 4, the Mystery Man enters and sits down in a clean office not seen anywhere else in the game, clearly unaffected by the world collapse. He chastises Goldman for being "soft", claiming that humans "have no need of hope", and that the "true end" shall begin. He also mentions the existence of another "Pandora's Box".
In the "true" ending of The House of the Dead 4: Special, he limps in the chamber where the Magician was defeated, he states that Pandora's Box has been closed, if there is any hope left. He then says the Wheel of Fate "cannot be stopped". On the Playstation 3 port, the trophy image for getting this ending is the Mystery Man's fully-revealed face.
According to an interview with series director Takashi Oda on the Website of the Dead, should another arcade sequel be developed, its story would be based around this character.
Little is known about the Mystery Man's identity and motives. While fan theories have materialized, all are unconfirmed and many were debunked.
The theory that he was Goldman, who perhaps had survived his suicide in The House of the Dead 2, was disproven in 4; Goldman's death is reaffirmed, and the Mystery Man's voice and appearance suggest that he is another character altogether. Takashi Oda also stated that The House of the Dead III was the Mystery Man's first appearance, debunking theories of Harry Harris from 2 and Papa Caesar from The House of the Dead: Overkill being his identity.
- "It appears they didn't understand its true purpose."- from The House of the Dead III.
- "Goldman, you are soft. These wretched humans have no need for hope. Soon the true end shall begin. There is more than one Pandora's Box."- from The House of the Dead 4.
- "So Pandora's Box has been closed. That is if there is any "hope" left. The Wheel of Fate cannot be stopped"- from The House of the Dead 4: Special.
- He appears different and slightly older in The House of the Dead 4 ending compared to what he looked like from The House of the Dead III ending. This is strange, as The House of the Dead III takes place several years after The House of the Dead 4. However, it might be because he was barely seen in the House of the Dead III ending, or that the developers of the game decided to slightly retcon his appearance.
- If you noticed in The House Of The Dead 4 ending, you can almost see that on the Mystery Man does not have a foot on his damaged leg.
- His middle-aged, gaunt appearance, widow peak hairstyle, and suit resemble the character the G-Man from the Half-Life series. Both are mysterious entities whose identities are undisclosed.
- His laugh in his The House of the Dead III ending is similar to Goldman's laugh from The House of the Dead 2.
- Canonically, he will survive House of the Dead: Scarlet Dawn due to it taking place thirteen years prior to The House of the Dead III.