David O'Brien (born August 3, 1963), nicknamed "OB", is an American sportscaster who is a lead play-by-play announcer on the New England Sports Network (NESN) for telecasts of the Boston Red Sox of Major League Baseball (MLB), and for college football and college basketball games aired on the ESPN Inc.-owned ACC Network.

He has previously broadcast for MLB's Atlanta Braves, Florida Marlins, and New York Mets, and has announced other sports including basketball, football, and soccer.

O'Brien broadcast for the Florida Marlins from the team's 1993 inaugural year through 2001, including their first World Series win in 1997.

O'Brien recorded play-by-play "commentary" for the High Heat Major League Baseball video game series for its 2002, 2003, and 2004 installments, along with color commentator Chuck Valenches.

Prior to the 2005 season, O'Brien was denied permission by ESPN to join the Chicago Cubs' broadcast team.

[3] In 2019, O'Brien returned to call college football games for the inaugural season of the ESPN Inc.-owned ACC Network, partnering with fellow New England native Tim Hasselbeck.

[4] O'Brien joined Marcelo Balboa on the primary broadcast team for the 2006 FIFA World Cup coverage on ESPN and ABC Sports, despite having no experience calling soccer matches prior to that year.

Because The Walt Disney Company, owner of both television outlets, retained control over on-air talent, the appointment of O'Brien as the main play-by-play voice was made over the objections of Soccer United Marketing, who wanted JP Dellacamera to continue in that role.

Disney stated that their broadcast strategy was intended, in voice and style, to target the vast majority of Americans who do not follow the sport on a regular basis.

[5][6] In 2007, O'Brien joined the Boston Red Sox Radio Network, calling games alongside primary play-by-play announcer Joe Castiglione.

And now it's just Barry Bonds and Hank Aaron, side by side.August 7, 2007 – O'Brien also called the game between the Giants and the Washington Nationals in which Bonds hit his 756th home run, breaking the record that had been held by Hank Aaron for more than 33 years.Bacsik's 3-2 again, there's a swing and a high fly ball, right center field!

And on the night of August 7, 2007 in San Francisco, California, Barry Lamar Bonds has hit more home runs than any major leaguer in the history of baseball.October 13, 2013 – O'Brien also called David Ortiz's grand slam off Joaquin Benoit in Game 2 of the 2013 American League Championship Series between the Boston Red Sox and the Detroit Tigers for WEEI-FM.Red Sox trailing 5-1 and Papi gets in.