Alfonso Guilleard Soriano (born January 7, 1976) is a Dominican-American former professional baseball left fielder and second baseman. He played in Major League Baseball (MLB) for the New York Yankees, Texas Rangers, Washington Nationals, and Chicago Cubs, and in Nippon Professional Baseball for the Hiroshima Toyo Carp.

Soriano began his professional career with Hiroshima in 1996, but signed with the Yankees as a free agent in 1998 and was assigned to play in minor league baseball. The next year, he was the Most Valuable Player (MVP) in the All-Star Futures Game, and made his MLB debut for the Yankees, with whom he would win two American League championships. The Yankees traded Soriano to the Rangers after the 2003 season, and the Rangers traded Soriano to the Nationals after the 2005 season. He signed a contract as a free agent with the Cubs before the 2007 season. The Cubs traded Soriano to the Yankees in 2013, and the Yankees released him in 2014.

Soriano was a seven-time MLB All-Star, and won the All-Star Game MVP Award in 2004. He won the Silver Slugger Award four times. He is one of only six players in the 40–40 club, achieving the feat in 2006. He played primarily as a second baseman for the Yankees and Rangers before being converted to an outfielder with the Nationals. Soriano is one of only 58 major league players to hit 400 or more career home runs, and was seventh among active players in home runs at the time of his retirement.

Soriano began his professional baseball career in Japan with the Hiroshima Toyo Carp, training at their Carp Academy for Dominican players. Soriano spent 1996 playing in Japan in the minor Western League. In 1997, he was promoted to the varsity team, and, wearing uniform number 74, he appeared in nine games, batting .118 (2 for 17) with two walks.

Soriano disliked the intense Japanese practice schedule, and the Carp denied him a salary increase from $45,000 to $180,000 per year. Like Hideo Nomo and Hideki Irabu, who had previously left Japan to play in the United States, Soriano hired sports agent Don Nomura to help his situation. After first attempting to void Soriano's Nippon Professional Baseball (NPB) contract by unsuccessfully arguing that the player was legally a minor when he signed it, Nomura advised him, like Nomo, to retire from NPB and pursue a career in MLB. This prompted Carp executives to file an injunction against Soriano, and to send letters to MLB teams demanding that they cease all negotiations with him. After the Nomo case, NPB officials had amended the Working Agreement without consulting any MLB officials in an attempt to prevent the situation from recurring. Since MLB had not agreed to any changes to the agreement, MLB Commissioner Bud Selig declared that MLB would recognize Soriano as a free agent on July 13, 1998 and the Carp backed down.

Soriano signed as a free agent with the New York Yankees in 1998, starting his career as an infielder, first as a third baseman, and then moving over to second base. Soriano was named to the All-Star Futures Game in 1999. He won the game's most valuable player award after hitting two home runs in the contest.

He played in New York for five seasons. His first hit in MLB came in 1999 when he hit a game-winning home run against Norm Charlton of the Tampa Bay Devil Rays. He finished in third place for Rookie of the Year honors in 2001. In the World Series that year, he hit the go-ahead home run off Arizona Diamondbacks pitcher Curt Schilling in the seventh game, but Arizona won anyway when Luis Gonzalez hit his series-winning single on a cut fastball by closer Mariano Rivera.

In 2002, Soriano became the second Yankee in franchise history to record 30 home runs and 30 stolen bases in the same season (the first being Bobby Bonds in 1975), then repeated the feat in 2003. Also in 2002, he led the American League with 696 at bats, 209 hits, 92 extra base hits, 41 stolen bases, 128 runs and set a Yankees' team record for most at bats (696) and most strikeouts (157) in a season.