Jean René Lacoste (July 2, 1904 - October 12, 1996) was a famous French tennis player and businessman, nicknamed "the Crocodile" or "the Alligator" by fans, because of his pugnacity on court; he is now mostly known as being the namesake of the Lacoste tennis shirt, which he introduced in 1929.

Lacoste was one of The Four Musketeers, France's tennis stars who dominated the game in the 1920s and early 1930s. He won 7 Grand Slam singles titles in the French, American, and British championships but never made the long trip to Australia to play in their championships. He was the World No. 1 player for both 1926 and 1927.

In 1933, Lacoste founded La Société Chemise Lacoste, together with André Gillier. The company produced the tennis shirt which Lacoste often wore when he was playing, which had an alligator (generally thought to be a crocodile) embroidered on the chest.

In his 1979 autobiography Jack Kramer, the long-time tennis promoter and great player himself, included Lacoste in his list of the 21 greatest players of all time.

There are numerous explanations of why Lacoste was originally nicknamed the Crocodile (or the Alligator). A 2006 New York Times obituary about Lacoste's son, Bernard, provides an apparently authoritative one. In the 1920s, supposedly, Lacoste made a bet with his team captain about whether he would win a certain match. The stakes were a suitcase he had seen in a Boston store; it was made of crocodile (or alligator) skin. Later, René Lacoste's friend Robert George embroidered a crocodile onto a blazer that Lacoste wore for his matches.

The week of his death, French Advertising agency Publicis, who had been managing the account for decades, published a print ad with the Lacoste logo and the English words "See you later...", reinforcing the idea that the animal was perhaps an Alligator.