(via https://en.wikipedia.org/wiki/Strongest_beer#Strength )
The strength of beers has climbed during the later years of the 20th century. Vetter 33, a 10.5% abv (33 degrees Plato, hence Vetter “33”) doppelbock, was listed in the 1994 Guinness Book of World Records as the strongest beer at that time, though Samichlaus, by the Swiss brewer Hürlimann, had also been listed by the Guinness Book of World Records as the strongest at 14% abv.
Samuel Adams reached 20% abv with Millennium and then surpassed that amount to 25.6% abv with Utopias.
The strongest beer brewed in Britain was Baz's Super Brew by Parish Brewery, a 23% abv beer.
In September 2011, the Scottish brewery BrewDog produced Ghost Deer, which, at 28%, they claim to be the world's strongest beer produced by fermentation alone.
Eisbock method of fractional freezing, in which a strong ale is partially frozen and the ice is repeatedly removed, until the desired strength is reached, a process that may class the product as spirits rather than beer.
Schorschbräu's 2011 Schorschbock 57 with 57,5%.
It was preceded by The End of History, a 55% Belgian ale, made by BrewDog in 2010.
BrewDog had previously made Sink The Bismarck!, a 41% abv IPA, and Tactical Nuclear Penguin, a 32% abv Imperial stout.
Schorschbräu's Schorschbock, a 31% abv eisbock, and Hair of the Dog's Dave, a 29% abv barley wine made in 1994
A 60% abv blend of beer with whiskey was jokingly claimed as the strongest beer by a Dutch brewery in July 2010.