Janusz Tadeusz Kusociński (January 15, 1907 - June 21, 1940) was a Polish athlete, winner of 10 000 m at the 1932 Summer Olympics.

Born in Warsaw into a family of railroad worker, Janusz Kusociński, or Kusy as he was nicknamed, played football in various Warsaw clubs as a schoolboy. He take up athletics in 1928 after joining the sport club "Sarmata". His coach there was a famous Estonian decathlete Aleksander Klumberg-Kolmpere.

In his first competition at Polish National Championships, Kusociński surprisingly won the 5000 m and cross country titles. He missed the next season, because he was called on duty to the Polish army, but he came back stronger as ever. He won the Polish Champion titles in 1500 m, in 5000 m and in cross country in 1930 and 1931 and in 800 m in 1932.

Just about a month before the Los Angeles Olympics, Kusociński runs a new world record in 3000 m (8:18.8) and later on that year, he sets a new unofficial world record in 4 miles (19:02.6). At the Olympics themselves, Kusociński wins a close battle against the Finns Volmari Iso-Hollo and Lasse Virtanen in 10 000 m with a world seasons best time 30.11.4.

After finishing second in the first European Championships at Turin in 5000 m, Kusociński decided to retire from athletics, but made a comeback in 1939 by winning the 10 000 m at the Polish National Championships.

Kusociński volunteered to the Polish army, after Poland was attacked by Germans and was wounded twice. Janusz Kusociński was arrested by gestapo on March 26, 1940 and was killed in a prison camp three months later.