Janus Lascaris (Greek: Ἰανὸς Λάσκαρις, Ianos Laskaris; c. 1445, Constantinople – 7 December 1535, Rome), also called John Rhyndacenus (from Rhyndacus, a country town in Asia Minor), was a noted Greek scholar in the Renaissance.

Lascaris entered the service of the Kingdom of France and was ambassador at Venice from 1503 to 1508, at which time he became a member of the New Academy of Aldus Manutius; but if the printer had the benefit of his advice, no Aldine work bears his name.

He resided at Rome under Leo X, the first pope of the Medici family, from 1513 to 1518, returned under Clement VII in 1523, and Paul III in 1534.

[1] In the meantime he had assisted Louis XII in forming the library of Blois, and when Francis I had it removed to Fontainebleau, Lascaris and Guillaume Budé had charge of its organization.

[1] Among his pupils were Alessandra Scala, Marco Musuro, Germain de Brie, Dimitrije Ljubavić, and Jacques Dubois.