Hungarian modern pentathlete who dominated the sport in the 1960s and is considered among the greatest of the storied line of Hungarian competitors in the modern pentathlon.

A strong swimmer and runner and a consistent fencer, Balczó won individual championships in 1963, 1965–67, and 1969. He also won five team championships with the Hungarian team. He was less fortunate in Olympic competition. In his debut at the 1960 Games in Rome, Balczó finished first in the swim and second in the run, but poor shooting left him in fourth place and off the medal stand. He missed the 1964 Olympics but returned to the Olympics at the 1968 Games in Mexico City. He was a favourite in the competition but won only a silver medal after a surprising performance by Björn Ferm of Sweden. He won gold medals in the team event in 1960 and 1968. Determined to earn a gold medal on his own, he returned to the individual Olympic competition in 1972 at Munich. In the final event, the cross-country race, he put forth a courageous effort to pass three other competitors and win the gold.