The Yokohama DeNA BayStars (横浜DeNAベイスターズ^?, Yokohama Dī-Enu-Ē Beisutāzu) are a professional baseball team in the Japanese Central League. Their home field is Yokohama Stadium, located in central Yokohama. The clubhouse is located near the stadium. The team has been known by several names since becoming a professional team in 1950. It adopted its current name in 2011 when the club was purchased by software company DeNA.

The minor league team shares the same name and uniform as the parent team and plays in the Eastern League. The minor league home field is Yokosuka Stadium, located in Yokosuka, Kanagawa.

The team began as the Taiyo Fishing Company, an amateur team currently affiliated with the Maruha Corporation (presently Maruha Nichiro). The team began to appear in national tournaments in the 1930s and won the National Sports Festival in 1948, giving it national recognition. In the 1949 off-season, the Japanese professional baseball league drastically expanded itself and many players from the Taiyo amateur team were recruited to join the professional leagues. The owner of the Taiyo company decided to join the newly expanded Central League, which was established in 1950. The team's first professional incarnation was as the Maruha Team. The franchise was based in Shimonoseki, Yamaguchi.

The team name was changed to the Taiyō Whales (大洋ホエールズ^?, Taiyō Hoeeruzu) shortly after the start of the 1950 season. The Whales received several veteran players from the Yomiuri Giants to compensate for their lack of players, but ended up in the bottom half of the standings each year.

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