Byttering (also Bytering, Bytteryng, or Biteryng; possible first name Thomas) (fl. c. 1400 – 1420) was an English composer during the transitional period from Medieval to Renaissance styles. Five of his compositions have survived, all of them in the Old Hall Manuscript.
A possible identification of Byttering with a Thomas Byteryng has been made. Byteryng was a canon at Hastings Castle between 1405 and 1408, and was a rector somewhere in London in 1414. There is no information on the composer in the Old Hall Manuscript other than that his surname is attached to several pieces. Those pieces stand out from many of the works in the manuscript by their relatively advanced stylistic traits.
Byttering's music includes three mass sections – two Glorias and a Credo – a motet based on Nesciens Mater, and a substantial three-voice, isorhythmic wedding motet, En Katerine solennia/Virginalis contio/Sponsus amat sponsum, his best-known work, which was almost certainly written for the wedding, on 2 June 1420, of King Henry V and Catherine of Valois.
The four-voice Gloria, No. 18 in the Old Hall MS, is one of the most complex canons of the early 15th century, and represents what was probably the extreme of stylistic differentiation between English and continental practice. Canons in continental sources are extremely rare, but there are seven in the Old Hall MS, and Byttering's is the only one with the standard arrangement of the same tune in all four voices.