According to Wiki only 4 guys have done it in tests as follows;
6 Sixes in an over
On 31 August 1968, Garfield Sobers became the first man to hit six sixes off a single six-ball over in first-class cricket.[4] The over was bowled by Malcolm Nash in Nottinghamshire's first innings against Glamorgan at St Helen's in Swansea. Nash was a seam bowler but—somewhat rashly, as it turned out—decided to try his arm at spin bowling. This achievement was caught on film.[5]
The feat was repeated by Ravi Shastri in January 1985. Playing for Bombay against Baroda at the Wankhede Stadium in Bombay, Shastri hit left-arm spinner Tilak Raj for six sixes in a single over.
On 16 March 2007, in a match between South Africa and the Netherlands at the 2007 Cricket World Cup, Herschelle Gibbs became the first person to hit six sixes off an over in a One Day International match. The over was bowled by Dutch leg-spinner Daan van Bunge.[6]
On 19 September 2007, in a match between England and India, Indian cricketer Yuvraj Singh hit six sixes off a single six-ball over in a Twenty20 international cricket match during the inaugural ICC Twenty20 World Cup in Durban, South Africa. The bowler was Stuart Broad of England.
However this not allow for county cricket etc where it probably has happened as well.
As to baseball, I get the gist but not the detail. Cricket is way simpler.....honest!