Door

A Door (or Hatch) is a pathway which leads Samus into new rooms. They have appeared in every Metroid game to date except Metroid Prime Pinball. Doors almost always feature low-level energy shields that can be disrupted by weapons fire. The most common type of door is the Blue Door, which can be opened with any type of weapon.

Many doors are covered with Blast Shields, which must be destroyed with a certain type of weapon before the door itself can be opened. The most common blast shield is the Red Blast Shield, which requires a Missile to open (in the original Metroid, and Super Metroid they had to be opened with 5 missiles).

In Super Metroid, onboard the Ceres Space Colony, there are doors that automatically open if someone is nearby. They do not require to be shot to open. They do appear to have a fail-safe protocol and automatically lock themselves, seen during the battle with Ridley.

In Metroid Fusion, the security hatches in the BSL station did not require specific weapons to open. Instead, Samus had to unlock each type of hatch in special Security Rooms hidden in various parts of the station. After each type of security hatch was unlocked, they could be opened with any weapon.

In Metroid: Other M, doors are either "Green," "Red." or "Orange." "Green" doors are doors that can be opened, "Red" doors are doors that cannot be opened, and "Orange" doors require a certain action to open. There are also types of Super Missile shields, Seeker Missile Shields, and Missile Shields. Doors now open automatically once unlocked and do not need to be shot, similar to those in the Ceres Space Colony.

Blue Doors
Encountered in every game except Metroid Fusion and Metroid: Other M these basic doors can be opened with any weapon.

Metal Doors
Encountered in Metroid: Zero Mission and Super Metroid. These doors will not open until a specific task has been completed.

Purple Doors
Violet doors that are opened with the Wave Beam. Found in Metroid Prime.

White Doors
White-fringed doors that are opened with the Ice Beam. Found in Metroid Prime.

Red and Orange Doors
These red or orange doors are opened with the Plasma Beam. Found in Metroid Prime and Metroid Prime 3: Corruption, respectively.

White Hatch
White-colored doors that are opened with the Light Beam. Found in Metroid Prime 2: Echoes.

Purple Hatches
Purple-colored doors that are opened with the Dark Beam. Found in Metroid Prime 2: Echoes.

Grey Hatches
Black-and-white-colored doors that are opened with the Annihilator Beam. Found in Metroid Prime 2: Echoes.

Green Doors
Green-colored doors that are opened with the Nova Beam. Found in Metroid Prime 3: Corruption.

Blast Shields
Blast Shields are found covering normal Blue Doors throughout the Metroid series. There are several varieties that all require Samus Aran to use different weapons to destroy them. Once they have been destroyed, however, all Blast Shields are gone for good.

Red Blast Shield
These red-colored blast shields are found in Metroid, Metroid II: Return of Samus, Super Metroid, Metroid: Zero Mission, Metroid Prime and Metroid Prime 2: Echoes. These doors are opened with 5 normal Missiles or a single Missile (in Zero Mission, Prime and Echoes only). They can also be opened with 1 Super Missile.

Green Hatch
Green Hatches from Super Metroid, Metroid: Zero Mission, and Metroid Prime 2: Echoes. These require one Super Missile to open.

Multi-Lock Blast Shields
Blast shields that can only be destroyed by hitting all of the locks simultaneously with Seeker Missiles. Found in Metroid Prime 2: Echoes, Metroid Prime 3: Corruption, and Metroid: Other M.

Yellow Hatch
These blast shields can be found in Super Metroid, Metroid: Zero Mission and Metroid Prime 2: Echoes. They can be opened with a Power Bomb.

White Blast Shields
These blast shields are found in Metroid Prime 3: Corruption. They are vulnerable to the Ice Missile and possibly other cold-based weaponry, although this has yet to be proven.

Mounted Blast Shields
Blast shields that are destroyed by using the Grapple Lasso to generate enough stress to pull them from their mounts. Found in Metroid Prime 3: Corruption.

Brown Blast Shields
First encountered in the Celestial Archives, Brown Blast Shields replace Red Blast Shields in Metroid Prime Hunters, and, like in the rest of the Prime games, they require one Missile to destroy.

Green Blast Shield
First encountered in the Celestial Archives, Green Blast Shields are only vulnerable to the Battlehammer.

Purple Blast Shield
First encountered on Alinos, Purple Blast Shields are only vulnerable to the Judicator, though they may also be vulnerable to other cold-based weaponry.

Yellow Blast Shield (Metroid Prime Hunters)
First encountered in the Celestial Archives, Yellow Blast Shields are only vulnerable to the Volt Driver, although they may also be vulnerable to other electricity-based weaponry.

Orange Blast Shield
First encountered on Alinos, Orange Blast Shields are only vulnerable to the Magmaul, but may also be vulnerable to other fire-based weaponry. They are similar to the Orange Doors in Corruption.

Red Blast Shield (Metroid Prime Hunters)
Red Blast Shields are only encountered on Arcterra. They are vulnerable to the Imperialist.

Biologic Space Laboratories research station Doors
Instead of having Doors or Blast Shields that require different weapons to open, the BSL station is equipped with various levels of security hatches. Areas that are hazardous or are crucial to the station's operations are often placed behind high-level hatches. In order to open them, Samus Aran must first find the appropriate Security Room and manually unlock the security level.

Gray Hatch
This is the lowest security level; hatches of this level are gray in color, and are the most common hatch seen on the station. Adam is able to unlock this level at the beginning of the game.

Blue Hatch
This is the second security level; hatches of this level are blue in color. Adam asks Samus to unlock the Blue Hatches in Sector 2 so she can reach the Bombs.

Green Hatch (Metroid Fusion)
This is the third security level; hatches of this level are green in color. Adam asks Samus to unlock the Green Hatches in Sector 3 so she can reach the Super Missiles.

Yellow Hatch (Metroid Fusion)
This is the fourth security level; hatches of this level are yellow in color. Adam asks Samus to unlock the Yellow Hatches in Sector 5 so she can reach the Ice Missiles. They do not exist outside of Sector 5.

Red Hatch
This is the fifth and final security level; hatches of this level are red in color. Adam never authorizes Samus to open Red Hatches in Sector 4, but she is forced to do so in order to get the Diffusion Missiles and return to a Navigation Room.

De-energized Door
This door appears in Metroid Prime and Corruption. Occasionally, some doors will not be active and Samus cannot use them. To restore power, she must energize one or more Power Conduits in the area with her Wave Beam in Prime, or weld back the missing wires with her Plasma Beam in Corruption.

Echo Gate
This door appears in Echoes. It is invulnerable to all weaponry. To open the door, Samus must activate the nearby Echo Key Beam system to lower the gate and destroy the Echo Key Beams.

Leviathan Door
This organic door appears in Corruption. They appear in Leviathan Seeds, and have a bone plate that retracts when shot.

Magma-eruption port
More or less a hatch, Anthony Higgs is ordered by Adam to destroy this door and let the Lava flow. Samus destroys it with her Super Missiles.

Phaaze Door
This organic door appears in Corruption. It is a maw and appears only on Phaaze, hence the name, and is similar to a Leviathan Door. The scan says it can only be opened with the Hyper Beam, but it is actually vulnerable to any weapon.

Sealed Door
This door appears in Hunters. It looks like a typical door, but with a spinning red lock on it. They behave exactly like Blast Shields.

Shutter
This door appears in most 2-D Metroid games. It is not actually a door, rather, it is a pole that is triggered when a switch or a certain location is shot.

Special Hatch
This hatch appears in Fusion. It behaves like a Sealed Door/Blast Shield, but is purple in color and harder than typical hatches. Usually, they will trigger when Samus is supposed to talk to Adam.

Stronghold Door
This door appears in Hunters. Arguably the largest door in the Metroid series, it has an electronic force field and behaves like any normal hatch. When shot, the color will dull, and it will slowly open. It most resembles a Leviathan/Phaaze Door.

Translator Door
This door appears in Echoes. It is a gate with a hologram of a message written in Luminoth (that reads GATE), and must be opened by scanning it. As Samus continues on, she will have to continually upgrade her Translator Module to read the hologram, which is in different colors (violet, amber, emerald and cobalt).

Telekinetic barrier
This door appears in Echoes. It appears to be a Luminoth-made door, as it only appears if Samus tries to leave the area she is in without returning the Energy to the Energy Controller, or if, in the Great Temple, she tries to avoid speaking to U-Mos.

Waste Disposal Unit
This door is a small hatch that only the Morph Ball can access. It appears in multiple games in the Prime Series.

"Yellow"/"Pink" Blast Shields
There are two Blast Shields of notable mention in the original Metroid. They are unnamed in the guides, and both are the only of their kind in the entire game. Both require 10 Missiles to open. The "Yellow Blast Shield" appears in Tourian in the first shaft. The "Pink Blast Shield" appears in Ridley's chamber, blocking the way to a room with an Energy Tank.

Trivia

 * In the Prime series, the doors acted as hidden loading screens, which is why some of them take so long to open.
 * The doors of Elysia in Metroid Prime 3: Corruption strongly resemble the doors of Metroid Prime. This is probably because both planets were also old Chozo colonies.
 * The doors of the Pirate Homeworld in Metroid Prime 3: Corruption also bear much resemblance to the doors in the classic games.
 * In Metroid Prime 2: Echoes, if a Metroid touches a door, it will explode instantly.
 * According to a scan, the Phaaze door can only be opened by a burst of Phazon. However, the scan is actually false; if Samus stands still without engaging the "permanent Hypermode", aims at the first door, and shoots it with the Nova Beam, its surrounding aura will disappear.
 * In Metroid: Other M, if an enemy somehow escapes their original room by exiting through an open door, they will attempt to return to their original room (provided they aren't attacking Samus) and "phase" through the wall.
 * Metroid Prime is the only three-dimensional game in which doors are placed vertically as well as horizontally. Super Metroid is the only two-dimensional game to have this feature.

Metroid Prime Hunters scan
"A weak energy shield surrounds the door to keep out roaming creatures. Any weapon will open this door."