a Roman rhetorician, who opened a school at Rome B. C. 81 (Hieronym. in Euscb. Chron. Olviymp. 174. 4.) The cognomen of Otacilius is uncertain. Sentonius calls him Pilitus (in some manuscripts Pilutus), Eusebius Plotus, and Macrobius. (Salturn. 2.2) Pitholaus. He had been formerly a slave, and while in that condition acted as door-keeper (osliarius), being chained, as was custonmary, to his post. But having exhibited talent, and a love of literature, he was manumitted by his master, and became a teacher of rhetoric. Cn. Pompeius Magnus was one of his pupils, and He wrote the history of Pompey, and of his father likewise, in several books, being the first instance, according to Cornelius Nepos, in which a history was written by a freedman. (Suet. de Ill. Rhet. 3; Voss. de Hist. Lat. 1.9. p. 40.)