Jānis Lūsis (born 19 May 1939) is a Latvian athlete who competed in javelin throw. In 2014 he was inducted into IAAF Hall of Fame.

Lūsis trained at Daugava Voluntary Sports Society and later at Armed Forces sports society. He competed in four Summer Olympics for the USSR team, winning bronze in 1964 Olympics, gold in 1968 Olympics and silver in 1972 Olympics.

The javelin competition at the 1972 Games was the closest in Olympic history. Germany's Klaus Wolfermann had taken the lead from Lūsis in the fifth round with an Olympic Record throw of 90.48 meters. Then, in the sixth and final round, Lūsis let fly with a very long effort that measured at 90.46 meters - Wolfermann's two centimeter margin was, at the time, the smallest unit of measurement used in javelin competitions.

As of 2003, he remains the only Latvian who has won a complete set of Olympic medals. Lūsis set two world records in javelin throw, of 91.68m in 1968 and of 93.80 m in 1972. He is also a 4-times European champion. In 1987 IAAF nominated him as the all-time greatest javelin thrower in the world.

After Lūsis finished competing, he became an athletics coach. He is married to Elvīra Ozoliņa, 1960 Olympic female champion in javelin throw. Their son, Voldemārs Lūsis, is also a javelin thrower who competed in 2000 Summer Olympics and 2004 Summer Olympics.

During the 2009 Latvian Sportspersonality of the year award ceremony, Lūsis received the Lifetime Contribution to Sport award.