Unknown Soldier may refer to:

• Tomb of the Unknown Soldier, a type of memorial site in many nations
• The British grave of The Unknown Warrior in Westminster Abbey
• Tomb of the Unknown Soldier (Arlington), United States memorial

• The Unknown Soldier (novel), a 1954 novel by Finnish writer Väinö Linna
• "Unknown Soldier" (short story), a short story by Kurt Vonnegut

• The Unknown Soldier (1926 film)
• The Unknown Soldier (1955 film), a Finnish film based on the novel by Väinö Linna
• Unknown Soldier (1968 film), a film by Donald Shebib
• The Unknown Soldier (1985 film), a Finnish film based on the novel by Väinö Linna
• The Unknown Soldier (1998 miniseries), a British miniseries featuring Aislín McGuckin
• The Unknown Soldier (2006 film), a German documentary film by Michael Verhoeven about the Wehrmachtsausstellung
• The Unknown Soldier (2017 film), a Finnish film based on the novel by Väinö Linna

• Unknown Soldier (Fela Kuti album), 1979
• The Unknown Soldier (album), a 1980 album by Roy Harper, or its title song
• Unknown Soldier (Warmen album), 2000, or its title song
• The Unknown Soldier (song), a 1968 song by the Doors
• "Unknown Soldier", a song by Breaking Benjamin, and is the fourth single from the album Phobia
• "Unknown Soldier", a song by the Casualties from On the Front Line
• "Unknown Soldiers", an anthem of Lehi

• Unknown Soldier (Ace Comics), a superhero character
• Unknown Soldier (DC Comics), the name of several distinct characters

• "Unknown Soldier" (The Unit), an episode of The Unit
• William Eckert or Unknown Soldier, Major League Baseball commissioner
• The Unknown Soldiers, protagonists of Forgotten Worlds

• Unknown Rebel
• The Unknown Warrior, in Westminster Abbey
• Unknown Child, a victim of the Titanic disaster