Jan-Ove Waldner, in Sweden commonly J-O Waldner (Swedish: [ˈjiː uː], is a Swedish former professional table tennis player. He is often referred to as "the Mozart of table tennis." A sporting legend in his native Sweden as well as in China, he is known in China as 老瓦 Lǎo Wǎ or 常青树 Cháng Qīng Shù, because of his extraordinary longevity and competitiveness. As of July 2023, he is the only person to win an Olympic table tennis gold medal representing a non-Asian country.

Table tennis is a racket sport derived from tennis but distinguished by its playing surface being atop a stationary table, rather than the court on which players stand. Either individually or in teams of two, players take alternating turns returning a light, hollow ball over the table's net onto the opposing half of the court using small rackets until they fail to do so, which results in a point for the opponent. Play is fast, requiring quick reaction and constant attention, and is characterized by an emphasis on spin relative to other ball sports, which can heavily affect the ball's trajectory.