The Unknown Soldiers are the playable protagonists in Forgotten Worlds.
The Unknown Soldiers (名なしの超戦士, roughly "Super Warrior with no Name") are flying marines battling aliens accompanied by a floating satellite. Their ultimate goal is to destroy the evil goddess Bios of Dust Planet.
There were no actual names given for the first appearance of these characters; all were referred to very generically. Storywise, they were secretly trained from the time they were young boys by a group of humans to combat the evil on Dust Planet. The duo did not have any names other than "Superior Warriors", as shown in the ending.
The blue Unknown Soldier appears as one of the many enemies in Adventure Quiz: Capcom World and Capcom World 2, while Sylphie appears as an INN owner in the latter and Capcom Quiz: Hatena? no Daibouken.
- In Capcom Baseball, the two Unknown Soldiers appear together in a newspaper ad for the CP System Arcade board together with Arthur and Strider Hiryu, the main characters in the first 3 games using said board.
- The blue Unknown Soldier appears in Marvel vs. Capcom: Clash of Super Heroes as a Special Partner, using the Satellite Option from Forgotten Worlds. One of the game's stages ("Headquarters of Evil") appears to be based on the final stage of the game (the Tower of Babel) and features the final three bosses (Whodin, Laidin and Bios) in the background. Bios also makes a cameo in the game's Secret File.
- The two Unknown Soldiers appear in the background of Ken's stage from Street Fighter Alpha 2, as two of several guests from other Capcom games.
- The Unknown Soldiers appear in Namco × Capcom as playable characters.
- In the first two games from the SNK vs. Capcom: Card Fighters Clash series the blue warrior also appeared in the Action card Mega Crush, and both warriors appear in a Reaction card.
- Characters heavily resembling the two Unknown Soldiers appear in the 2nd volume of the Archie Mega Man comic book.