The first cricketer to hit 6 sixes in an over is Sir Gary Soberse.
If your question is with relevance to first class cricket then the great ":Sir Gary Sobers": from the West Indies, was the first cricket player to hit 6 sixes in an over, it came in a county game between Nottingham and Glamorgan, at St Helen’s in Swansea, against the bowling of Malcolm Nash. Equally unfortunate was fielder Roger Davis, who caught the ball – only to have his catch disqualified as he fell over the boundary
":Ravi Shastri": from India repeated this feat in a ranji trophy match in 1995.
However ":Herschelle Gibbs": of South Africa is the first cricketer to have accomplished this feat in International Cricket and that too in a World Cup Match. It is worth mentioning this effort although it was against minnows Netherlands. He scored off Daan Van Bunge in the 30th Over.
Gary Sobers &: Ravi Shastri had hit 6 sixes in First class cricket while Gibbs had hit for the first time in One dayers &: also in World Cup matches.
Sir Garfield Sobers of westindies was a first person to hit six sixes in an over but Herchiel Gibbs from South Africa hit six sixes in a single over in the ICC worldcup 2007.
Sir Garfield Sobers for county cricket match
and Herrs Gibbs in international but Netherlands is a weak cricketing side
Garfield(Gary) Sobers was the !st ever in a first class game.
This feat was repeated by Ravi Shastri, also in a first class game.
Herschelle Gibbs did it for the first time in an international against The Netherlands a few days ago
Sir Gary Sobers
Sir Gary Sobers
1. Gary (garfield) sobers (West Indies) (county cricket)
2. Ravi shastri (county cricket)
3. Herschel Gibbs (South Africa) (ICC WC 2007)