Introduction.
While playing Majora's Mask it is unavoidable to notice many of the characters that appear in Hyrule also make an appearance in Termina as well. But these persons are not the same as the ones that appear in Hyrule, even thought they may be physically identical. The reason for this is that Termina is confirmed to be a parallel dimension to Hyrule. The LoZ community has denominated these characters "Terminian Counterparts".

Knowing this, some people have wondered about Majora's Mask and it's counterpart(If it truly has one). It is normal to wonder why such a great evil power wouldn't have a parallel. Many people, including myself, believe this parallel is the fused shadow mask from TP. This is what this topic is about.

Recognition: Before I begin, I would like to point out this was not completely my Idea. I was inclined to make this topic when I was reading some very interesting arguments concerning this idea. I then decided to make a well-organized topic that explained this theory with more depth.


Here are some short descriptions of both masks:

Majora's Mask:MM is an ancient artifact that was used by an ancient tribe, but the mask's wicked power became so great that it was sealed away to prevent a great catastrophe.

Fused Shadow:The Fused Shadows hold the magical power used by the Dark Interlopers who sought entry to the Sacred Realm to claim the Triforce. The enormous power of the Interlopers was sealed away within the Fused Shadow by the Gods. The Fused Shadow was then shattered, it's pieces concealed deep within the temples of Hyrule.


Alright then. With these ideas understood, we can begin the theory.

1-"A Tale of Two Masks"
Let's explore the origins of both masks in order to find similarities.

Majora's Mask
Fused Shadow
Similarities:
a)The ancient tribes:You may have noticed that the tribe described in MM sounds very familiar to the Twili. In MM it says that this tribe created the mask that had tremendous dark powers, fearing it's power. In TP the light spirits sealed the dark powers of the Twili in the Fused shadows. This story is a little different, but we have to remember these two tribes are counterparts of each other and are not the same entirely. Both tribes have been mentioned in-game to have immense dark powers and both of their powers are sealed in masks. The resemblance is uncanny.
b)Both tribes "Vanished" : Neither of the tribes are seen in their respective worlds of origin. We know the Twili are in the twilight realm, but what about the tribe in MM? Well, considering the Twilight realm is not a part of Hyrule nor Termina, the tribe in MM could have been sent there as well, or to a world parallel to the Twilight Realm. Which raises the question: Are both tribes the same? or are they parallels of each other?
c)Power:Both stories clearly state that both masks award great power to the user.This will be better explained in the next section.



2-Power
As explained in their respective storylines both masks grant exceptional powers to the ones who use them.

While wearing Majora's mask the skull kid was able to accomplish incredible feats such as: Curse various characters, shatter the great fairies to pieces, call upon the moon, etc...

While wearing the Fused Shadows Midna's powers were almost limitless, as she destroys impenetrable barrier guarding Hyrule castle. It is also responsible for creating the huge explosion in the final boss battle.

Both masks are proven to contain dark and ancient great powers. This similarity says a lot right here.


3-Visual similarity.


These two picture show the similarities.
- The most obvious similarity is the eye design. Both mask's eyes are almost identical to each other. This is the best fact as many cultures believe the eyes are the gateway to the soul.
-Both masks present markings and symbols.

3-Pieces and Remains
In TP we see the four pieces of the fused shadows. One is on midnas head and the other three are in their respective temples. In MM we have the four boss remains who seem to have a conection to Majora because of their appearance in the final battle.

We can easily connect the number 4 here in both masks. Yet another fact they both share.


4-Zant and Majora
This may be a coincidence, but you can notice the fighting style of Zant, a Twili, and Majora's Incarnation are the same.


5-Counterpoints
In the same way there is evidence suggesting them to be counterparts there is evidence suggesting otherwise.

a-Most of the counterparts are identical in appearance. Although MM and FS share similarities they can hardly be considered identical.
b-Some people believe MM is simply the manifestation of evil in Termina, the same way Ganon is the manifestation of evil in Hyrule. It is possible majora is Ganon's counterpart.
c-Majora has life of it's own. The Fused Shadow isn't known to share this attribute.

The masks' parallel nature has never been confirmed by Nintendo and is merely speculation and good judgment, as are all of the theories here.

Well, thanks for reading and fell free to post your opinion on this.