- Born: <Penrhyn, Llandegai, Caernarfonshire>, Wales
- Marriage (1): Sir Thomas Salusbury
Other names for Janet were Jonet verch William Griffith and Jonet vz William Griffith.
Source: The History of the Princes, the Lords Marcher, and the Ancient Nobility of Powys Fadog, and the Ancient Lords of Arwystli, Cedewen, and Meirionydd by J. Y. W. Lloyd, Vol. II (London, 1882), p. 333
Janet married Sir Thomas Salusbury. (Sir Thomas Salusbury died in 1505.)