Meaning and name origin
Gareth \g(a)-re-th\ as a boy's name is pronounced GARE-eth. It is of Celtic origin, and the meaning of Gareth is "gentle". Sir Gareth, noted for his modesty and bravery, was a knight of King Arthur's Round Table. Literary: the name appeared in the 15th century in Sir Thomas Malory's "Le Morte D'Arthur". It may have been a form of Geraint, or be linked to Welsh gwaraidd meaning "gentle". Gary, which is actually an independent name, is often used as a pet form of Gareth.
Gareth is not a popular first name for males and an equally uncommon surname or last name for all people (2000 U.S. Census).
Displayed below is a comparison of the popularity of the boy name Gareth and its variant forms. Popular variation forms ranked in the Top 1000/100 are Gary (#560), Garth and Garret. (2014 statistics).