Teseida (full title Teseida delle Nozze d’Emilia, or ‘The Theseid, Concerning the Nuptials of Emily’) is a long epic poem written by Giovanni Boccaccio c.1340–41. Running to almost 10,000 lines divided into twelve books, its notional subject is the career and rule of Theseus (Teseo), although the majority of the epic tells the story of the rivalry of the love of Palemone and Arcita for the love of Emilia. It is the main source of "The Knight's Tale" in Geoffrey Chaucer's the Canterbury Tales, and therefore is the original source of "Two Noble Kinsmen" a collaboration by William Shakespeare and John Fletcher. The exact sources of Boccaccio's knowledge about the ancient Greek world are unknown, but is likely that he gained the knowledge through his close friendship with Paolo de Perugia, a medieval collector of ancient myths and tales.
Jeanne de la Font gained fame in the sixteenth century by writing a French verse adaption of Teseida.