Jason Gilbert Giambi (/dʒiˈɑːmbi/; born January 8, 1971) is an American former professional baseball first baseman and designated hitter.

In his Major League Baseball (MLB) career, which began in 1995, Giambi played for the Oakland Athletics, New York Yankees, Colorado Rockies, and Cleveland Indians.

Giambi was on the baseball team, whose roster also included his brother Jeremy and three other future major league players: infielder Shawn Wooten, pitchers Aaron Small and Cory Lidle.

[citation needed] The Oakland Athletics selected Giambi in the second round (58th overall) of the 1992 Major League Baseball draft.

[3] He started his career that year with the short-season Single-A Southern Oregon A's of the Northwest League, where he hit .317 in 13 games.

[citation needed] Giambi hit two home runs in Oakland's 2000 season opener on April 3, the first Athletics player to ever do so.

He led the league for the second year in a row in both on-base percentage (.477; a career best, and still the highest OBP in the AL since 1995) and walks (129).

Both years, he led the Athletics to the postseason, both times losing in the American League Division Series to the New York Yankees in five games.

[14] Giambi ended the 2005 season leading the major leagues in walk percentage (20.6%)[15] and leading the American League in walks for the fourth time in his career (109), and in OBP for the third time in his career (.440, as well as in fly ball percentage (47.7%);[16] second in MLB to Todd Helton), and had an OPS of .975, placing him fifth in the AL.

On September 3, 2008, Giambi walked into a bathroom door in his hotel room while in Florida before playing against the Tampa Bay Rays.

The accident caused him to split his eyelid open but he played through the injury later that night and went 1-for-4 with one RBI, helping the Yankees win the second game of the series.

[18] On September 21, 2008, Giambi recorded the final hit in Yankee Stadium, when he drove in Brett Gardner with an RBI single.

[19] Giambi ended the season with a home run every 14.3 at-bats, beating out Alex Rodriguez to lead the team by a small margin.

[26] At the time, Giambi had the lowest batting average in the majors, and fourth-lowest slugging percentage in the American League.

[27] Looking for a veteran bat to help their playoff push, the Colorado Rockies agreed to a deal with Giambi on August 23, 2009.

His first RBI with the Rockies came in the form of a bases loaded walk in his first plate appearance on September 1, 2009, after being promoted to the club upon roster expansion earlier that day.

[31] On September 12, Giambi hit a walk-off home run against the Arizona Diamondbacks, extending the winning streak for the Rockies to 10 games.

[32] The Colorado Rockies announced on January 17, 2011, a deal to put Giambi in the team's minor league organization with a spring training invite for the 2011 season.

[34] Giambi became a free agent after the 2012 season and was a finalist for the Rockies major league managerial opening, which eventually went to Walt Weiss.

[38] He broke his own record for oldest player to hit a walk-off home run in a season saving win for the Indians against the White Sox on September 24, 2013.

[44] Late in 2003, Giambi was named by FBI officers investigating the Bay Area Laboratory Co-operative (BALCO) as being one of the baseball players believed to have received anabolic steroids from trainer Greg Anderson.

[45] In December 2004, the San Francisco Chronicle reported it had seen Giambi's 2003 grand jury testimony in the BALCO investigation.

The newspaper said that in his testimony, Giambi admitted to using several different steroids during the off-seasons from 2001 to 2003, and injecting himself with human growth hormone during the 2003 season.

[46] In a press conference prior to the 2005 season, Giambi apologized publicly to the media and his fans, though he did not specifically state what for.

Giambi is one of the owners of Casa Cielo (also owned by Scott Deskins of SCC Development in Austin, Texas) in Cabo San Lucas, Mexico.

Giambi also appeared in The Bronx Is Burning, a television drama that debuted on ESPN in 2007, as a taxi cab driver.