What does Gareth mean?
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.
How popular is Gareth?
Gareth is an uncommonly occurring first name for males. Gareth is an uncommon surname too for both adults and children. (2000 U.S. Census)
Shown below is a comparison of the popularity of Gareth and associated names. Garret, Garry, Garth and Gary (#560 2 years ago) are the prominent alternative forms of Gareth (not ranked) listed in the Top 1000. Other forms, like Jeraint, are uncommon. Usage of these forms of Gareth was more pronounced during the years 1960-1969 (usage of 0.5663%) and has become much diminished since (usage 0.11%, 80.6% less). (2014 Birth Statistics)