Bele Regis Notarius ("notary of Béla the King"), most often referred to as Anonymus (Latin for "unnamed"; fl. late 12th century – early 13th century) was the notary and chronicler of a Hungarian King, probably Béla III. Little is known about him, but his latinized name began with P, as he referred to himself as "P. dictus magister". Some scholars suggest that he was Péter, the bishop of Győr.
Anonymus is most famous for his work Gesta Hungarorum ("The Deeds of the Hungarians"), written in Latin around 1200. This work provides the most detailed history of the arrival of the Hungarians to the Carpathian Basin (Hungarian: honfoglalás), although historians don't accept his work as authentic. Most of his attempts to explain the origin of several Hungarian place names are unsupported by modern etymology. The names of the seven chieftains of the Hungarians are known from his writings.
The only surviving manuscript is from the 13th century and is in the National Széchényi Library in Budapest. It has been translated to Hungarian by István Lethenyey, canon of Pécs (1791), István Mándy (1799) and Károly Szabó (1860).
It is known from his Gesta Hungarorum that he was from the upper Tisza region and was tightly connected to the Aba family of that region. In the preface, he wrote that he studied in Western Europe (probably Paris), where he learned the genre in which he wrote his Gesta.