Louis William "Lou" Merloni (born April 6, 1971) is an American radio personality and a former Major League Baseball player. Merloni was scouted by hall of fame scout 'Buzz' Bowers, and played for his hometown Boston Red Sox from 1998-2003. Merloni is well-known locally for his frequent trips between the Red Sox and their Triple-A affiliate, the Pawtucket Red Sox, which has become known as the "Merloni Shuttle" . He also played for the San Diego Padres, Cleveland Indians, and Los Angeles Angels of Anaheim.

Merloni was nicknamed "Sweet Lou" by Boston fans since he was born in Framingham, Massachusetts. He graduated from Providence College in 1993 and still holds several single-season and career records for the now-defunct Friars baseball team.

Merloni was a replacement player during the 1994-95 Major League Baseball strike and is therefore barred from membership in the Major League Baseball Players Association.

Merloni is known for hitting a home run in his first major-league at bat in Fenway Park, a 3-run home run off of José Rosado on May 15, 1998.

After beginning the 2006 season in Triple-A, Merloni was called up to the Cleveland Indians on May 17, 2006. Merloni signed a contract with the Oakland Athletics for the 2007 season. He played the season for the A's Triple-A affiliate, the Sacramento River Cats. Merloni was chosen as the Most Valuable Player in the 2007 Bricktown Showdown, leading the River Cats over the Richmond Braves by a final score of 7-1. He was also voted Best Defensive Player and Best Teammate for the 2007 season. Merloni contributed a home run and 4 RBI in the game. Before the game, Merloni was chosen as the River Cats' team captain.

Beginning in March 2008, Merloni began appearing on WEEI-AM's Big Show as a co-host. On May 27, 2008, Merloni joined the New England Sports Network (NESN) as a commentator on the Red Sox pre-game and post-game shows. After the 2008 season Merloni decided not to remain with NESN. Merloni was hired by Comcast SportsNet New England during the 2009 season as an analyst and reporter.

In the offseasons of 1996 and 1997, Merloni served as a substitute gym teacher at Framingham High School, where he attended high school.

On June 6, 2010, it was announced Merloni would be inducted into the Cape Cod Baseball League Hall of Fame as part of their 2010 Class on November 20. He played for the Bourne Braves in 1991 and the Cotuit Kettleers in 1992.

On February 28, 2011, Merloni started co-hosting WEEI's Mut and Merloni with Mike Mutnansky. On May 27, 2014, Lou was joined by former New England Patriots tight end Christian Fauria and Tim Benz, a former beat reporter for the Pittsburgh Steelers and radio show host in Pittsburgh, to form "Midday's with MFB" after Mike Mutnansky was forced out of the show due to poor ratings.

In 2013, Merloni began serving as a part-time color analyst on Red Sox radio, teaming with play-by-play announcers Joe Castiglione and Dave O'Brien for select games. In October of that year he joined Castiglione and O'Brien for WEEI's broadcasts of the ALCS and World Series.