| Gwenllian ferch Gruffydd | |
|---|---|
| Princess consort of Deheubarth | |
| Born | c. 1097 Aberffraw, Anglesey (Ynys Môn), Kingdom of Gwynedd |
| Died | 1136 (aged 38–39) Kidwelly Castle, Kidwelly (Cydweli), Wales |
| Spouse | Gruffydd ap Rhys, Prince of Deheubarth |
| Issue | Morgan ap Gruffydd Maelgwyn ap Gruffydd Gwladus ferch Gruffydd Nest ferch Gruffydd Owain ap Gruffydd Maredudd ap Gruffydd Rhys ap Gruffydd Sion ap Gruffydd |
| House | Aberffraw |
| Father | Gruffudd ap Cynan |
| Mother | Angharad ferch Owain |
Gwenllian ferch Gruffydd () (Gwenllian, daughter of Gruffydd; c. 1097 – 1136) was a 12th century Welsh rebel and Princess consort of Deheubarth. The daughter of Prince of Gwynedd Gruffudd ap Cynan and member of the House of Aberffraw, she married Gruffydd ap Rhys, the Prince of Deheubarth, and would lead a "patriotic revolt" with him during the Great Revolt of 1136 until her death at the battle at Kidwelly Castle.
Her death would serve as a rallying cry for Welsh rebels, and she became a symbol of Welsh independence. There are several notable artistic depictions of Gwenllian, often depicting her with a sword in hand, or riding a chariot into battle in the style of Boudicca. She is sometimes confused with Gwenllian ferch Llywelyn, who lived two centuries later.