Alvin Christian "Al" Kraenzlein (December 12, 1876 – January 6, 1928), known as "the father of the modern hurdling technique", was an American track-and-field athlete, and the first sportsman in the history of Olympic games to win four individual gold medals in a single discipline at the 1900 Summer Olympics in Paris.
Before, Carl Schuhmann, a German athlete, won four Olympic titles in gymnastics and wrestling at the 1896 Summer Olympics in Athens.
As of 2016, Alvin Kraenzlein is the only track-and-field athlete who has won four individual titles at one Olympics.
Kraenzlein is also known for developing a pioneering technique of straight-leg hurdling, which allowed him to set two world hurdle records.
He is an Olympic Hall of Fame (1984) and USA Track & Field (1974) inductee.