So something I decided I wanted to make a lore post on is the deities and legends of the three realms, though it's a little on the shorter/rougher side. I'll admit this is a combination of Minecraft Legends stuff, Minecraft Dungeons stuff, and a heavy dusting of my own original ideas.
The Overworld is known for the Hosts, worshipped by a number of groups in the overworld throughout time. The three hosts are known as Foresight, Knowledge, and Action.
Foresight is a long, serpentine creature, with a number of eyes across their body. Four main eyes keep them locked on the present, while the others are clouded by visions of the future. Foresight can see many possible futures, but is unable to change them in any way.
Knowledge is a small creature, who is unwilling to let themself be seen, obscuring their body beneath the crafting grid they carry upon their back. Knowledge is endlessly creating things, but has a tendency to discard most of them in anger, finding them useless or imperfect.
Action is a large creature of stone. When peaceful, they are covered in vegetation, but when angered, Action's body will become like a raging volcano, magma and lava seeping from cracks in their stone body. Their anger becomes directionless and all in their path will feel it.
Many villages to this day follow the Hosts, the only ones really left in the modern day who believe in them, often believing that it is important to balance the aspects of the three. Knowledge is no good if there's no foresight or action taken, foresight requires action and knowledge to be of use, and directionless, uninformed actions can cause more harm than good.
In the Nether, Piglins tell great tales of Gods that fight incredible battles, such as the first Piglin, the Great Hog, and the Two Kings, the King of Wither and the King of Blaze.
The King of Wither is a giant bipedal skeleton, dripping with a black poison. It stands with a hunched posture, its bones seeming mismatched. It is held together by fungus, carrying a massive sword that seems to be made of bedrock itself. The King of Wither is said to spread all manner of fungus and disease.
The King of Blaze is a being made of molten metal, magma, and fire, its form shifting frequently. It is mostly a humanoid structure, seemingly made of crude metallic armor, melted and reformed again and again.
The two kings were the first beings in the Nether. The two would begin an endless fight back and forth, creating the landscape of the Nether as they battled. Lakes of lava, fungal forests, basalt deltas and all aspects of the harsh realm. However, after many years of fighting, the kings grew older and tired. Both would lay to rest eternally, the King of Blaze is said to be at the bottom of the deepest lake of lava in the Nether. The King of Wither is said to have buried itself beneath the soul sand valleys.
The Great Hog is something of a demigod figure to the piglins, said to have been the first piglin, born after the war of the two kings ended. He was said to have discovered gold and forge it into a mighty sword, and to have chased down a number of creatures in an endless hunt. Many stories of his have been forgotten, but he is still influential in Piglin culture. The first Piglin Emperor was known to have named himself after the Great Hog.
The End has only one deity, as I mentioned in my End lore post. This God is the mysterious Ender, a creature of indeterminate form. Once the only inhabitant of the void, Ender was said to give every part of its form to create life within the void and the Enderlings. When the realm was finished, only Ender's heart and soul remained, said to lie at the deepest, most remote part of the End.
Very little evidence of the worship of Ender remains, only crumbling temples and old sigils. Why the remaining Endermen abandoned their deity is unknown.
In both the Overworld and Nether, many individuals have told of a strange figure, player-like in stature, but with unnatural abilities and glowing white eyes. The figure has been spotted since before the fall of the players. Players and villagers regarded him as a mysterious spectral force, bringing strange happenings and monsters in his wake. His name is said to be Herobrine, an old name whose meaning is lost to time. A number of stories and rumors of his origin have been told time and time again, details embellished or mixed together, or forgotten to time.
In the Nether, Piglins have regarded him as a being that brings destruction and misfortune, as it is said that he was spotted within the deepest parts of the Nether Fortress, just days before the fall of the Piglin Empire.