Llewelyn I, also known as Llewelyn the Great, was a prominent Welsh prince who ruled from 1205 to 1240. He played a crucial role in unifying various Welsh territories and resisting English domination. His leadership helped to establish a sense of Welsh identity and autonomy during a time of political fragmentation. Llewelyn I is best known for his efforts to strengthen the Principality of Gwynedd, which became a powerful center of Welsh culture and politics under his reign. He also engaged in diplomatic relations with other kingdoms, including England, to secure his position and protect Welsh interests.