Iorwerth mab Owain Gwynedd (or Iorwerth Drwyndwn meaning "the flat-nosed"), (c. 1130–1174), was the eldest legitimate son of Owain Gwynedd (the king of Gwynedd) and his first wife Gwladys (Gladys) ferch Llywarch. He married Marared ferch Madog.
Iorwerth mab Owain Gwynedd, also known as Iorwerth Drwyndwn ("flat-nosed"), (born around 1130 and died in 1174) was the eldest legitimate son of Owain Gwynedd, king of Gwynedd, and his first wife Gwenllian ferch Llywarch. He married Marared ferch Madog.