Carlos is the eldest of four children born to Felipe and Mery Peña. The family moved to the United States when Carlos was young, initially living with one of Carlos' uncles in Haverhill, Massachusetts.
He graduated from Haverhill High School in 1995. He initially went to Wright State University in Dayton, Ohio, but returned home after a semester and instead went to Northeastern University. As a collegiate player, he competed in the Cape Cod League, which showcases top amateur prospects every summer. He was a member of the Wareham Gatemen in 1997. 
Peña began his professional career in 1998, playing for three different Rangers affiliates. Prior to the 1999 season, Peña was named by Baseball America as the 93rd prospect in their top 100 prospects list. In 1999, Peña played for the Charlotte Rangers, the Rangers Advanced Single-A team. He batted .255 with 18 home runs in 138 games.
Peña appeared in Baseball America's top 100 prospect list in 2001, this time appearing at #11 and was also the Rangers top prospect. He advanced another level in 2001, this time playing for the Oklahoma Redhawks, the Rangers Triple-A affiliate. He played in 119 games for the Redhawks in which he batted .288 with 23 home runs and 74 RBIs. Peña was also a Triple-A All-Star in 2001.
Following the 2001 minor league season, the Rangers called him up to the big leagues during September of 2001, when rosters expanded. Peña made his Major League debut on September 5, starting at first base and going 0-3. Peña finished the 2001 season with a .258 batting average and 3 home runs in 22 games played.
Prior to the 2002 season, Peña once again appeared on Baseball America's Top 100 Prospect list again and was #5 on the list. Peña was on the Athletics Opening Day roster and his starting first baseman's job was a job to lose. He did lose the job when he was demoted to the Triple-A Sacramento River Cats on May 21. Peña had played in 40 games and batted only .218 with 7 home runs and 16 RBIs. He was named the American League Rookie of the Month for the month of April in which he batted .264 with 7 home runs and 16 RBIs; his 7 home runs was one shy of the record for most home runs in a month by a rookie. Peña would go on to play in 44 games for the River Cats in which he batted .240 with 10 home runs and 33 RBIs.
During Peña's stint with Sacramento, he hit .438 with 2 home runs and 6 RBIs from July 2-July 5. Following this small hot streak, Peña was involved in a three team deal on July 6, 2002. The Athletics had sent Peña, a player to be named later (was later named as Jeremy Bonderman), and Franklyn Germán to the Detroit Tigers. The New York Yankees sent Ted Lilly, John-Ford Griffin, and Jason Arnold to the Athletics. The Tigers sent Jeff Weaver to the Yankees and cash to the Athletics.
The Tigers had acquired him due to a season ending injury to designated hitter Dmitri Young and the first baseman at the time of the trade for the Tigers was Randall Simon who immediately became the Tigers designated hitter following Peña's acquisition.
Peña made his Tigers debut the next day, on July 7, against the Boston Red Sox. He went 3-4 with 2 doubles and 2 RBIs. Peña played in 75 games for the Tigers in 2002 and batted .253 with 12 home runs and 36 RBIs. Overall he batted .242 with 19 home runs and 52 RBIs in 115 games. His 2002 season included a 12 game hitting streak from September 8-September 21, which tied teammate Omar Infante for the longest hitting streak for an American League rookie in 2002.
Peña played in his first full season in 2003 as the Tigers everyday first baseman. On May 19, against the Cleveland Indians, he established career highs with 3 home runs and 7 RBIs. Peña also missed nearly a month in June when he was out with a left calf strain. He played in 131 games for the Tigers in 2003 and batted .248 with 18 home runs and 59 RBIs.
In 2004, Peña established career highs in games played (142), at bats (481), hits (116), doubles (22), home runs (27), runs scored (89), RBIs (82), total bases (227), stolen bases (7), walks (70), and strikeouts (146). Pena also batted .241 in 2004.
On May 27, 2004, against the Kansas City Royals, Peña matched a Tigers nine inning single game record with a career high six hits. He became the fifth player in franchise history to do so and the first one since Damion Easley accomplished it on August 8, 2001, against the Texas Rangers. He batted in the eighth spot in the batting order and his six hits were the most from the eighth spot since Wilbert Robinson of the Baltimore Orioles collected seven hits on June 10, 1892 against St. Louis.
Peña began the 2005 season as the Tigers' starting first baseman again. After playing in 40 games in which he batted .181 with 3 home runs and 14 RBIs, Peña was demoted to the Triple-A Toledo Mud Hens. He played in 71 games for the Mud Hens and batted .311 with 12 home runs and 71 RBIs. Following an injury to shortstop Carlos Guillén, Peña was recalled on August 17. Following his recall, he put on a power show, hitting 15 home runs in 38 games. Overall, he played in 79 games for the Tigers in 2005, and batted .235 with 18 home runs and 44 RBIs.
While with the Detroit Tigers Pena hit the longest home run in Comerica Park clearing the bleachers in right-center as it took one bounce and left the stadium. The home run was hit to the deepest part of the ballpark.
New York YankeesEdit
Peña signed a minor league contract with the New York Yankees on April 15, 2006. He played at the Triple-A level for the Columbus Clippers. Playing in 105 games, he batted .260 with 19 home runs and 66 RBIs. On August 16, 2006, Peña exercised a clause in his contract and became a free agent.
Boston Red SoxEdit
The next day, on August 17, 2006, Peña signed a minor league contract with the Boston Red Sox and was assigned to Triple-A Pawtucket. With the Pawtucket Red Sox, Peña played in 11 games and batted .459 with 4 home runs and 8 RBIs. His contract was purchased on August 28, 2006. On September 4, 2006, Peña hit his only home run of the 2006 season. He was a defensive replacement and when he came up to bat in the bottom of the ninth, he hit a walk-off home run off Brandon McCarthy of the Chicago White Sox.
Peña ended up playing in 18 games for the Red Sox in 2006. He batted .273 with 1 home run and three RBIs. Following the season, he elected free agency.
Tampa Bay RaysEdit
Peña signed a minor league contract with the then-Tampa Bay Devil Rays (now "Tampa Bay Rays") on February 1, 2007. He was also invited to Spring training. Peña played in 23 games during Spring Training and batted .255 with no home runs and 4 RBIs. With his disappointing performance, the Rays reassigned Peña to minor league camp. With a knee injury to Greg Norton on the last day of Spring Training, the Rays re-signed him, this time to a Major League contract on April 1.
Peña was on the Rays active roster throughout the whole 2007 season. Peña had a slow start to his 2007 season, batting just .213 with four home runs in the month of April as a backup player. Peña got hot in May, hitting .356 with six home runs and 15 RBIs as an everyday player and was the Rays everyday first baseman for the rest of the season. He had four multi-home run games from August 26 to September 22.
Peña would go on to have the best season of his career in 2007 and set numerous career highs. He finished the season with a .282 batting average, 46 home runs and 121 RBIs. His batting average, home runs, and RBIs were career highs, as well as games played (148), at bats (490), runs scored (99), doubles (29), total bases (307), on-base percentage (.411), slugging percentage (.627), walks (103), and strikeouts (142). He was second in the American League in home runs to Alex Rodriguez's 54. His home run, RBIs, slugging percentage, on-base percentage and walk totals also set Rays franchise records. In 2007, he had the lowest range factor of all AL league first basemen, 8.73. While his team did not advance to the playoffs, Peña's season led him to being named the 2007 American League Comeback Player of the Year and his name has even been considered as an AL MVP candidate. He also was named the Player's Choice AL Comeback Player of the Year by fellow players. With this award he is allowed to donate $20,000 to Dominican youth under the poverty line. 
In 2008, Peña has struggled thus far, having compiled only a .227 batting average through 207 at-bats through June 4, 2008. He has, however, been able to maintain his power stroke, as evidenced by his eleven home runs on the year. A day after going 2-3 with a home run and three runs batted in against the Boston Red Sox, Peña was placed on the fifteen-day disabled placed on June 4, 2008 due to a broken finger.
- Major League Baseball hitters with three home runs in one game
- List of top 500 Major League Baseball home run hitters
- Career statistics and player information from MLB, or ESPN, or Baseball-Reference, or Fangraphs, or The Baseball Cube
|AL Comeback Player of the Year|
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