Scriptor Incertus de Leone Armenio ("unknown writer on Leo the Armenian") is the conventional Latin designation given to the anonymous author of a 9th-century Byzantine historical work, of which only two fragments survive.

The first fragment, preserved in the 13th-century Vat. gr. 2014 manuscript (interposed into descriptions of the Avaro-Persian siege of Constantinople and the Second Arab Siege of Constantinople, as well as hagiographical texts) in the Vatican Library, deals with the 811 campaign of Emperor Nikephoros I (r. 802–811) against the Bulgars, which ended in the disastrous Battle of Pliska.^[1] Discovered and published in 1936 by I. Dujčev, it is also known as the Chronicle of 811, or the Dujčev Fragment.^[2][3]

The second, which is preserved in the early 11th-century B.N. gr. 1711 manuscript in the Bibliotheque Nationale in Paris along with the chronicle of the so-called "Leo Grammaticus", deals with the reigns of Michael I Rhangabe (r. 811–813) and Leo V the Armenian (r. 813–820) that followed after Nikephoros I.^[1] The date of authorship is disputed, but the vividness of the narrative suggests that it was written by a contemporary of the events described.^[1]

The two fragments were identified^[4] as forming part of the same work by Henri Grégoire based on similarities in style. Although generally an unreliable indicator, this hypothesis has since been commonly accepted.^[1] Both fragments provide information not included in the contemporary histories of Theophanes the Confessor and Theophanes Continuatus, and Grégoire hypothesized, again based on style, that the Scriptor Incertus was a continuation of the work of the 6th-century historian John Malalas.^[1] The second fragment was known to, and used by, the late 10th-century Pseudo-Symeon Magister, but he does not appear to have used it for the sections of his history before Michael I.^[1]