Alexander I of Russia
The unexpected death of the Emperor far from the capital caused rumours that his death and funeral were staged so he could spend the rest of his life in solitude.  Some say the former emperor became a monk in Pochaev Lavra or Kievo-Pecherskaya Lavra or elsewhere.  A mysterious hermit, Feodor Kuzmich, (or Kozmich) emerged in Siberia in 1836, died near Tomsk in 1864 and was eventually glorified as a saint of the Orthodox Church.  Many people, including some historians, have theorized that he was Alexander I under an assumed identity.  While there are testimonies that "Feodor Kozmich" in his earlier life might have belonged to a higher level of society, claims that he was Alexander I were never proved.