Joan Princess of Gwynedd ^{1 2 3}

   Other names for Joan were Joan Princess of North Wales, Joanna Lady of Wales, Siwan and Joan Plantagenet Princess of Gwynedd.

  Research Notes:

Natural daughter of John, king of England. John had another, legitimate, daughter named Joan, who was Queen Consort of Alexander II of Scotland.
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From Ancestral Roots, Line 29A-27:
"JOAN, (nat. dau. by unknown mistress [of John "Lackland"]), Princess of North Wales, b. well bef. 1200, d. 30 Mar. 1236 or Feb. 1237..."
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Source - Wikipedia - John of England and Llywelyn the Great.

From Wikipedia - Llywelyn the Great:

"During Llywelyn's boyhood Gwynedd was ruled by two of his uncles, who had agreed to split the kingdom between them following the death of Llywelyn's grandfather, Owain Gwynedd , in 1170. Llywelyn had a strong claim to be the legitimate ruler and began a campaign to win power at an early age. He was sole ruler of Gwynedd by 1200, and made a treaty with King John of England the same year. Llywelyn's relations with John remained good for the next ten years. He married John's illegitimate daughter Joan , also known as Joanna, in 1205, and when John arrested Gwenwynwyn ab Owain of Powys in 1208 Llywelyn took the opportunity to annex southern Powys. In 1210 relations deteriorated and John invaded Gwynedd in 1211. Llywelyn was forced to seek terms and to give up all his lands east of the River Conwy, but was able to recover these lands the following year in alliance with the other Welsh princes. He allied himself with the barons who forced John to sign Magna Carta in 1215. By 1216 he was the dominant power in Wales, holding a council at Aberdyfi that year to apportion lands to the other princes...

Children
The identity of the mother of some of Llywelyn's children is uncertain. He was survived by nine children, two legitimate, one probably legitimate and six illegitimate. Elen ferch Llywelyn (c.1207-1253), his only certainly legitimate daughter, first married John de Scotia, Earl of Chester. This marriage was childless, and after John's death Elen married Sir Robert de Quincy , the brother of Roger de Quincy, Earl of Winchester . Llywelyn's only legitimate son, Dafydd ap Llywelyn (c.1208-1246), married Isabella de Braose, daughter of William de Braose, 10th Baron Abergavenny , Lord of Abergavenny. William was the son of Reginald de Braose , who married another of Llywelyn's daughters. Dafydd and Isabella may have had one child together, Helen of Wales (1246-1295), but the marriage failed to produce a male heir.

Another daughter, Gwladus Ddu (c.1206-1251), was probably legitimate. Adam of Usk states that she was a legitimate daughter by Joan, although some sources claim that her mother was Llywelyn's mistress, Tangwystl Goch.[64] She first married Reginald de Braose of Brecon and Abergavenny, but had no children by him. After Reginald's death she married Ralph de Mortimer of Wigmore and had several sons.

The mother of most of Llywelyn's illegitimate children is known or assumed to have been Llywelyn's mistress, Tangwystl Goch (c.1168-1198). Gruffydd ap Llywelyn (c.1196-1244) was Llywelyn's eldest son and is known to be the son of Tangwystl. He married Senena, daughter of Caradoc ap Thomas of Anglesey . Their four sons included Llywelyn ap Gruffydd , who for a period occupied a position in Wales comparable to that of his grandfather, and Dafydd ap Gruffydd who ruled Gwynedd briefly after his brother's death. Llywelyn had another son, Tegwared ap Llywelyn, by a woman known only as Crysten.

Marared ferch Llywelyn (c.1198-after 1263) married John de Braose of Gower, a nephew of Reginald de Braose, and after his death married Walter Clifford of Bronllys and Clifford. Other illegitimate daughters were Gwenllian ferch Llywelyn, who married William de Lacey, and Angharad ferch Llywelyn, who married Maelgwn Fychan. Susanna ferch Llywelyn was sent to England as a hostage in 1228, but no further details are known."

Joan married Llywelyn the Great Prince of Gwynedd, son of Iorwerth Drwyndwn ap Owain Gwynedd Prince of North Wales and Marared ferch Madog ap Maredudd, in 1205. (Llywelyn the Great Prince of Gwynedd was born about 1173 in <Dolwyddelan, Conwy>, Wales, died on 11 Apr 1240 in Cistercian Abbey of Aberconwy, Wales and was buried in Llanrwst Parish Church, Wales.)

  Marriage Notes:

Source: Ancestral Roots of Certain American Colonists Who Came to America before 1700 by Frederick Lewis Weis and Walter Lee Sheppard, Jr, ed. by William R. Beall & Kaleen E. Beall, Baltimore, 2008, Line 29A-27 has m. 1206. Wikipedia has m. 1205.