A Failed Incarnate is someone who was the intended Nerevarine, the reincarnation of Indoril Nerevar, as dictated by the Nerevarine Prophecy of Azura. All of these people were thought to be "possessed" by the spirit of the warlord, but had critical flaws that made them destined to fail the fulfillment of the prophecy, and as such were revealed to be false Nerevarines. Many failed incarnates have come and gone since the First Era, but came to an end when the true Nerevarine fulfilled the Prophecy in 3E 427.
The first known intended Nerevarine was Ane Teria, who was a holy crusader of the Tribunal Temple during the Tribunal's golden age in the early First Era, some time after the Battle of Red Mountain in 1E 700. She wrote writings, later known as Apographa, that were suppressed by the Tribunal Temple. She followed the false gods unquestionably, and only began to believe the Nerevarine Prophecy when it was too late.
In the late years of the Tribunate, Idrenie Nerothan was an incarnate who demoralized and repelled the Akaviri invaders during the First Akaviri Invasion in 1E 2703. She knew nothing of Dagoth Ur and the Nerevarine Prophecy until she took refuge with the Ashlanders. She died trying to loot Kogoruhn, the Sixth House capital in the northern Ashlands, considering her actions foolish.
Erur-Dan, another incarnate, saw Morrowind make a treaty with either the Reman Empire during the Four Score War, or the Septim Empire during the Tiber Wars. Humiliated by the surrender, he swore vengeance against the Empire and Tribunal alike. In later years, he despaired, and died fighting the Blight creatures at Red Mountain.
During the Akaviri Invasions of 2E 572, an incarnate named Conoon Chodala led fellow Ashlanders against the eastern invaders as the Imperials fled. He quested deep into House Dagoth's strongholds and Red Mountain, killing evil creatures where they stood, becoming gulakhan of his people. Chodala went on to become the ashkhan of the Urshilaku tribe, and began his quest to unite the tribes after being named Nerevarine. He made a pact with Clavicus Vile for the powerful staff Sunna'rah, and allied himself with the violent Red Exiles. Chodala used the staff to channel the god Vivec's divine energy for himself, making him increasingly reckless and overly confident, and each use weakening the god to the point where it almost killed him. He attempted to topple both the Tribunal and the Great Houses, seeking to go to war with them rather than earn their recognition as Hortator. His sister Seryn challenged his claim, causing them each to plea their cases to Wise Woman Dovrosi on whether Chodala was a true Nerevarine. With the help of the Vestige and the statements of previous failed incarnate, Chodala was indeed found to be a failed incarnate, turning on his tribe and fleeing to Kaushtarari for the favor of Malacath. His use of the staff was disabled using a Tonal Inverter, and Chodala perished fighting the Vestige and Seryn at the shrine, with the staff later being used by Barbas for the tasks of Clavicus Vile. Chodala's downfall came from craving glory, failing to see his real enemies.
In the waning years of the Second Era, Hort Ledd was the intended incarnate. He was a thinker and not a doer, and though chosen by the prophecy, he was not a hero and did not fulfill the prophecy. He died around 3E 27, in the last days of turmoil and unrest under the Septim Empire's rule over Morrowind.
Peakstar was an incarnate who survived the Blight, but fell in battle with an Ash Vampire. She did not master the arts of war, and did not learn the ways of the Great Houses, so she could not be named Hortator. In 3E 427, her spirit guided the true Nerevarine, helping them fulfill the prophecy.