Traditionally, Samus Unmasked is one of the appearances Samus Aran may take in the ending of a Metroid game. This is often the reward for players completing the game in a fair amount of time: fast enough to see Samus Unmasked, but not fast enough to see her in an Ending Outfit or Zero Suit.
In Super Metroid, Samus Unmasked can be seen by completing the game between three and ten hours. This is one of the few instances where Samus is shown to be wearing a visor or headset underneath her helmet, since much of her face remains obscured even with the helmet removed.
Some games show Samus Unmasked without requiring the player to fulfill certain conditions. Metroid Prime ends with Samus taking off her helmet while surveying the destroyed Artifact Temple; even if the player collects less than 75% of items, they can still catch a quick glimpse of Samus Unmasked just before the screen fades to black. In Metroid Prime 3: Corruption, Samus takes off her helmet while in the Bryyo Leviathan Core to vomit due to Phazon Fever.
Metroid II: Return of Samus, Metroid Prime 2: Echoes, Metroid Prime Pinball, Metroid Prime Hunters, Metroid: Other M, and Metroid Prime: Federation Force are the only games that do not feature Samus Unmasked in any endings (or in the game at all, for that matter).
On page 181 of Metroid: Zebes Invasion Order, Space Pirates successfully remove Samus's helmet and are silently shocked to discover her true identity. This is one of the earliest depictions of Samus as a human female (since most comics and adaptations tended to depict Samus as a cyborg male). She is shown with long black hair in this appearance.
The Nintendo Comics System often depicted Samus Aran without her helmet. This is first seen in the final panel of The Coming of a Hero, and is frequently seen throughout Deceit Du Jour when Samus is not actively battling enemies. Notably, these comics mark the first consistent appearance of Samus as a blonde.
The tendency to show Samus without her helmet continues into the Captain N: The Game Master comics, where Samus joins the cast. In her debut in Money Changes Everything, Samus is introduced wearing her full Power Suit, and then takes off her helmet to reveal her identity, much to the surprise of her teammates.
"It's said that the orphaned Samus Aran was raised by the few survivors of the Chozo race. They armed her with a Power Suit and taught her the ways of advanced combat; even burdened with her heavy suit, Samus is as graceful as a butterfly. In the Metroid series, it was standard that Samus would remove her helmet and armor if you cleared the game fast enough."
Game: Metroid (08/89)
"You got the Samus Unmasked trophy! Lucky you!"
- The Samus Unmasked trophy is the only appearance of a (somewhat) suitless Samus in Melee, and the first appearance of her face in 3D. Metroid Prime would be the first canon game to feature her face in 3D.
- Interestingly, Samus in the trophy and the ending of Prime are posed the same, standing in the Power Suit holding her helmet, with a short ponytail.
- The Samus Unmasked trophy is the first time Samus was seen to have a red hairband with her ponytail. The Zero Suit would later feature it.