Jānis Lūsis (born May 19, 1939 in Jelgava, Latvia) is a Latvian athlete who competed in javelin throw.

Lūsis competed in four Summer Olympics, winning bronze in 1964 Olympics, gold in 1968 Olympics and silver in 1972 Olympics. 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.

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