Mehrunes Dagon is the Daedric Prince of Destruction, Change, Revolution, Energy, and Ambition. He is associated with natural dangers like fire, earthquakes, and floods. He is an especially important deity in Morrowind, where he represents its near-inhospitable terrain as one of the Four Corners of the House of Troubles. In most cultures, though, Dagon is merely a god of bloodshed and betrayal. Dagon's plane of Oblivion is known as Deadlands. As the name suggests, they are barren wastelands, consisting of blackened isles in a sea of lava. The Dremora, Clannfear and Scamps are among his servants.

Dagon's acknowledged enemy is Ebonarm and his summoning day is Warriors Festival. He assisted Jagar Tharn in his temporary procurement of the Imperial throne, probably in anticipation of the decade of warfare and strife Tharn's rule produced. He invaded and seized control of the Battlespire, in contravention of the Daedric pact limiting meddling in mortal affairs by divine beings, in order to cripple the capacity of the Imperial College of Battlemages (which presented a threat to Tharn's power as Emperor). Dagon was also responsible for the destruction of Mournhold at the end of the First Era and apparently destroyed Ald Sotha, home of House Sotha and Sotha Sil's birthplace. Dagon was also the alleged inventor of the Daedric Crescent. The Broadsword of the Moon Reiver is an artifact created from Dagon's own substance and given to his Dark Seducer bodyguard, which was used against him by an unknown hero and resulted in the destruction of the Battlespire.

Dagon was the driving force behind the Oblivion Crisis. He plotted to destroy the Septim bloodline and open gates to Oblivion throughout Cyrodiil to launch an invasion. His motivation for this invasion is unclear; the Mythic Dawn claimed Nirn was Dagon's plane to begin with, but a more plausible explanation is that the ambitious Dagon was not content with Oblivion, where, unlike the mortal world, nothing he killed would truly die. The Mythic Dawn, diehard Dagon worshippers, worked to bring about the coming of Dagon by assassinating the Emperor and his three known heirs. The cult focused on the eternal dawn on which Dagon would come to cleanse the world of all non-followers. In order to recover the Amulet of Kings and foil Dagon's plans, the Champion of Cyrodiil had to recover the Mysterium Xarxes, a book written by Dagon himself, so that Martin Septim could open a portal to the Paradise of Mankar Camoran, where the amulet was being kept. Dagon himself made a short but dramatic appearance as a gigantic four-armed humanoid armed with an axe and talons at the climax of the Crisis.

Mehrunes' Razor is an ebony dagger much coveted by the Dark Brotherhood for its ability to kill anything in an instant. The Brotherhood has apparently also fallen prey to it, however, as the dagger was most likely involved in an internal struggle which decimated the organization roughly eighty years before the Warp in the West. It resurfaced when the Hero of Daggerfall received the Razor as a reward for exterminating a rogue Frost Daedra. Mehrunes' Razor was once in the possession of House Telvanni Councilor Neloth, and the humorous account of how he lost it can be read in the book Realizations of Acrobacy.

The Nerevarine was later tasked with the recovery of Mehrunes' Razor. In Cyrodiil, the Champion of Cyrodiil investigated rumors about the lost Ayleid city of Varsa Baalim being uncovered. It was revealed that the Drothmeri army, led by rogue Telvanni Arch-Mage Frathen Drothan, was attempting to locate the Nefarivigum, an evil construct Dagon created centuries ago to test pilgrims seeking Mehrunes' Razor. The Champion ultimately defeated Drothan and claimed the Razor.