Siôn Dafydd Rhys

Siôn Dafydd Rhys
Born1534
Llanfaethlu, Anglesey, Wales
Diedc.1609
Clun Hir, Brecknock, Wales
NationalityWelsh
Other namesLatin: Joannes David Rhaesus
Occupation(s)Physician and grammarian
Known forCambrobrytannicae Cymraecaeve linguae institutiones et rudimenta (1592)

Siôn Dafydd Rhys, in Latin Joannes David Rhaesus, also called John David Rhys, or John Davies (1534 – c.1609), was a Welsh physician and grammarian. He wrote the first Welsh grammar in Latin (but not the first Welsh grammar at all, see Gruffydd Robert), published in 1592.