Mystery Man

This unnamed man, also known as The Mystery Man by fans, is a mysterious man who appeared in the House of the dead series. He is a business suit who walks with a noticeable limp, who appears to be set up as the next main antagonist of the series, following Curien and Goldman. He first appeared in one of the endings for The House of the Dead III, and appeared again in one of the endings for The House of the Dead 4 and Special.

History
Not much is known about the Mystery Man and as such, his true identity is still unknown. In his first appearance, a brief glimpse of his face could be seen. Since nothing else was known at the time, many have speculated his true identity, with the most prominent being Goldman, or that he may be the successor Goldman was talking about at the ending of HOTD2.

The Mystery Man was a separate person with a different appearance and voice. He was shown to harbor a strong contempt for humanity, believing they are beyond hope, unlike his colleague Goldman. It has yet to be revealed what his motives and goals are, as well as his previous ties to both Curien and Goldman.

The House of the Dead 4 (comes before HOTD3)
In one of the endings, he enters and sits down in a clean office not seen anywhere else in the game, clearly unaffected by the world collapse. He chastises Goldman by saying he was soft and humans have no need of hope, and that the "true end" shall begin. He also mentions the existence of another "Pandora's Box".

The House of the Dead 4: Special
In the good ending, he appears in the lab 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.

The House of the Dead 3
In one of the endings, he is seen walking in the chamber where the Wheel of Fate was defeated and picks up a glowing canister revealed earlier as Daniel's cure. As he holds it in his hands, he chuckles to himself saying, "It appears that he didn't understand its true purpose," and then walks off.

Trivia

 * 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. Although it could be because he could barely be 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 the damaged leg.
 * He had a resemblance to the character the G-Man from the Half-Life series. He even had a middle aged gaunt appearance, plus a widow peak hairstyle like the G-Man, and is seen dressed in a suit. The G-Man is also a mysterious entity in the Half-Life series, with his real identity not disclosed.
 * His laugh in his ending in The House of the Dead III somewhat resembles Goldman's laugh from The House of the Dead 2