List of Metroid endings

Most Metroid games have featured endings that are received based on difficulty level, game completion, and/or play time.

Metroid
Samus stands on the surface of Zebes in all endings while performing one of several actions.

Metroid II: Return of Samus
Samus runs throughout the credits, jumps high, and lands, with either one of these events occuring.

Super Metroid
Samus will do either of the following, and then jump offscreen, before falling down and firing a blast.

Shortly before this, she is forced to escape Zebes, and she has the option of saving the trapped Dachoras and Etecoons. If she does, a white light will be seen leaving the exploding planet.

Metroid Fusion
Samus, in her Omega Suit, will be shown in various poses, before one of the following ending pictures appears:

Japanese endings
The Japanese versions contains an additional set of endings that show images of Samus' past. Linking to Metroid: Zero Mission with the Nintendo GameCube Game Boy Advance Cable will unlock all endings, including Japanese-only endings, and an additional two new endings, for a special gallery.

Additional endings
In addition, these two endings are present with the gallery in Zero Mission, and cannot be found in Fusion.

Metroid Prime
All endings depict Samus standing atop her starship, looking at the destroyed Artifact Temple with her helmet removed. Also, back at the Impact Crater, Dark Samus is born from Metroid Prime's remains.

Metroid: Zero Mission
Samus will stand against a space background in various poses before clenching her fist. Each ending, upon acquisition, will be added to a gallery in the menu. The endings for Metroid Fusion can be unlocked by linking the two games with the Nintendo GameCube Game Boy Advance Cable.

Metroid Prime Hunters
These endings are not affected by item percentage or clear time, rather, by fulfilling the Alimbic Prophecy and defeating Gorea's second form.

Metroid Prime 2: Echoes
Samus will wave farewell to the Luminoth before reaching her gunship. However, after Samus leaves Aether, Dark Samus can be seen forming in the midst of space.

Metroid Prime 3: Corruption
Samus will appear out of nowhere when it appears she had been lost in the destruction of Phaaze. She then heads to SkyTown, Elysia to mourn her fallen comrades before heading off into the unknown. Meanwhile, an unidentified space ship appears and follows Samus.

Trivia

 * Endings may have been inspired by that of Alien and Aliens, films from which Metroid was heavily inspired. At the end of both films, the female protagonist, Ripley, is scantily clad as she prepares for hypersleep.
 * The only games that do not have endings are Metroid: Other M and Metroid Prime Pinball. However, the former game makes up for this by having Zero Suit Samus become playable during the Countdown sequence, while Pinball has no sort of ending at all, except for Metroid Prime's core form exploding and Samus rolling away in Morph Ball, with a voice saying "Awesome."